From the moment of registration, the health of the woman and the fetus is closely monitored by obstetrician-gynecologists. Throughout the entire gestation period, the pregnant woman undergoes routine examinations. Some of the problems found can be solved therapeutically or surgically, others require termination of the pregnancy. One of the mandatory diagnostic methods that allows you to find out the parameters of fetal development is fetometry. How is fetometry done and what indicators are considered the norm?
What is fetometry and what is its purpose?
To have an idea about the development of the child (normally it passes or there are deviations), doctors need to constantly monitor the performance of the fetus. One of the planned examinations, which is prescribed to all women, regardless of the individual characteristics of the course of gestation, is fetometry.
What does fetometry include? This is the definition of the size of the fetus - height and weight. In ultrasound diagnostics, the following indicators are considered key (their abbreviation in Russian and English and decoding):
- MP, FW - mass;
- KTP, CRL - coccyx-parietal size;
- BDP, BPD – biparietal head size of the embryo;
- DB, FL - size of the femur;
- OC, AC - abdominal circumference;
- OG, NS - head circumference;
- LZR, OFD - fronto-occipital size.
Fetometry is performed using ultrasound. A pregnant woman undergoes sonography according to the plan in each trimester - at 11-14 (most often 12th) weeks, 18-21 weeks and at 32-33 weeks. As a rule, sonography is performed in the usual way through the abdominal cavity or transvaginally. Special preparation for the study is not required, only in the first trimester before a transabdominal examination, a woman needs to drink 1 liter of water 1 hour before visiting the office so that the bladder is full.
Only by fetometry it is impossible to draw conclusions about the correct development of the fetus. The parameters of the child will largely depend on his genetic and individual characteristics. If the mother and father are large, then the baby will be ahead of their peers in development. In case of growth retardation, a second ultrasound scan is prescribed after 2 weeks, often the baby manages to catch up by this time.
What is evaluated at the first ultrasound?
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The first screening ultrasound is sent shortly after the woman is registered. The optimal date for ultrasound diagnostics is 11–12 weeks, but if a pregnant woman went to the antenatal clinic later, she can be sent for sonography right away. Why is the screening examination scheduled for these periods? One of the most significant indicators in the early stages of gestation is the thickness of the nuchal space of the embryo. Previously, this parameter is indistinguishable, and after the 14th week it is filled with lymph, which distorts the readings.
Normal performance
At the first ultrasound, the doctor measures the heart rate of the fetus, looks at the presence of vital organs. Also pay close attention to the following parameters:
- TVP - the area between the soft tissues that cover the spine and the inner surface of the skin. Allows you to detect chromosomal abnormalities, such as Down syndrome.
- KTP - coccygeal-parietal size. It calculates the size of the fetus and the gestational age.
The table contains the norms of the results of ultrasound in the 1st trimester:
What does an embryo look like compared to a fruit? Until the first month, it resembles a poppy seed in size. By the end of the second month, it corresponds to a large grape of 5 cm. During the first fetometric study, it is comparable to a ripe fig of 7 cm.
What is considered abnormal and why?
To determine the norm and deviations in medical practice, the concept of percentiles is used. Among a large sample, the average value is determined - it is called the 50th percentile. The norm of ultrasound is in the range of 5-95 percentiles, and everything that goes beyond these limits is regarded as a deviation.
Non-compliance with normal values indicates the possibility of intrauterine diseases and developmental anomalies:
- Increased TVP often indicates the presence of genetic pathologies, which include Down's syndrome. Its probability is indicated by a high TPT rate, which stands for the thickness of the prenasal tissue. If a discrepancy is found, the woman is sent for additional examinations - analysis for alpha-fetoprotein, hCG, amniocentesis, placentocentesis, cordocentesis.
- Irregular heart rhythm may be due to congenital heart disease or hypoxia. Tachycardia and bradycardia can indicate oxygen starvation.
- A high KTR, which is 1–2 weeks ahead of the values, is considered the norm by doctors. Most often, this indicates that the child will be large. If the mother has diabetes mellitus or the likelihood of developing an Rhesus conflict is increased, then additional examinations are required.
- If deviations in the fetal anatomy are detected (incorrect anatomy of the bones of the cranial vault, spine, stomach, heart, limbs, abdominal wall), the sonologist enters them in a special column. Together with an obstetrician-gynecologist and, if required, geneticists, a conclusion is made on the advisability of prolonging gestation.
What indicators are studied in the second trimester?
Previously, ultrasound diagnostics in the second trimester was performed at the 25th week of pregnancy, but now it is performed at the 4th month of gestation. This is due to the need to detect malformations at an earlier stage. In addition to the parameters of the fetus during this period, they study the children's place, its size and degree of maturity.
Standard sizes
In the second trimester of pregnancy, you can better consider the size of the baby and specific organs. During this period, more attention is paid to the following indicators of ultrasound:
- baby weight;
- growth;
- abdominal circumference;
- fronto-occipital size;
- biparietal head size;
- leg size;
- thigh length;
- humerus size;
- forearm bone length.
The table shows the results of fetometry in the 2nd trimester in accordance with the protocol:
Week of gestation Weight, g Length cm coolant, mm OG, mm LZR, mm BPR, mm DG, mm dB, mm DP, mm DKP, mm 16 week 100 11,6 88–116 112–136 41–49 31–37 15–21 17–23 15–21 12–18 17 week 140 13 93–131 121–149 46–54 34–45 17–25 20–28 17–25 15–21 18 week 190 14,2 104–144 131–161 49–59 37–47 20–28 23–31 20–28 17–23 19 week 240 15,3 114–154 142–174 53–63 41–49 23–31 26–34 23–31 20–26 20 week 300 16,4 124–164 154–186 56–68 43–43 26–34 29–37 26–34 22–29 On the second screening study, it is already possible to estimate the size of the placenta. At week 20, it fluctuates between 1.67–2.86 cm. Amniotic fluid index by week:
- 16 – 74–202;
- 17 – 78–212;
- 18 – 81–221;
- 19 – 84–226;
- 20 – 87–231.
What are deviations from the standard?
The advanced maturation of the placenta is most often observed in smoking mothers. In addition, this indicator is affected by the presence of diabetes mellitus, the development of preeclampsia, the appearance of intrauterine infections.
Polyhydramnios indicates malformations in the development of the child, Rhesus conflict. Oligohydramnios indicates severe abnormalities in intrauterine development, pathologies or the absence of kidneys in the fetus.
Visualization can be difficult due to the high content of subcutaneous fat. In this case, the doctor indicates in the protocol the cause of the difficulty - PZHK.
The second screening ultrasound allows you to detect pathologies of fetal development that were not visible at the first examination:
- developmental delay, if the indicators are symmetrically below the specified norm;
- asymmetric reduction of the femur, humerus, tibia and forearm indicate skeletal dysplasia;
- an increase in the skull indicates hydrocephalus;
- by measuring the face, one can judge the presence of such pathologies as cyclopia, anophthalmia, cleft lip and palate;
- scanning the spine helps to detect its splitting;
- the absence, underdevelopment or abnormal structure of the internal organs indicate intrauterine anomalies that are incompatible with life.
Fetometry parameters of the fetus in the third trimester
The third fetal ultrasound is prescribed for 32–33 weeks of gestation, although, according to individual indications, the period can be shifted by several weeks. During this period, the baby is already fully formed, and it becomes possible to assess malformations that were not visible before. Particular attention is paid to the placenta and amniotic fluid, as well as fetal presentation.
Table of sizes of the fetus, body parts and organs are normal
The final fetometry is important, because it is according to its results that doctors choose the method of conducting the birth process. In the final trimester, the average data on the size of the baby and its weight are also evaluated.
The table shows the average fetometry in the third trimester:
On ultrasound, the obstetrician-gynecologist looks at the presentation of the fetus, the tactics of delivery depends on this:
- direct head presentation - natural delivery;
- oblique, transverse or direct pelvic presentation - caesarean section (as a rule).
Possible deviations and their interpretation
Deviations from normal indicators allow predicting possible complications during the birth process and detecting congenital malformations. Interpretation of deviations:
- Weight and height are more than normal. A large baby will complicate the delivery process. This may be an indication for surgical intervention, otherwise the woman in labor will rupture when the child passes through the birth canal.
- Low location of the placenta. In such a situation, natural childbirth is acceptable, but the risk of bleeding is high.
- In the third trimester, anomalies that did not appear before become visible. On the last examination, you can find a cleft lip, a cleft palate, an aneurysm of the vein of Galen.
- Indicators below the norm allow diagnosing developmental delay syndrome. This diagnosis allows you to take timely measures to maintain the life of the baby.
Rules for decoding the result of an ultrasound specialist
The interpretation of ultrasound during pregnancy is performed only by a sonologist, and the diagnosis is made by an obstetrician-gynecologist, who is based on the indicators of ultrasound diagnostics and other methods. Calculation of indicators is based on obstetric weeks, which are counted from the date of the last menstruation. In fact, the fetus is 1.5–2 weeks younger, but in order to avoid errors in calculations, gynecologists use a reference system from the first day of menstruation.
One of the main rules that specialists follow when deciphering ultrasound is not to make a diagnosis based on the results of sonography alone. If an abnormal course of gestation is suspected, the pregnant woman is prescribed a second examination and sent for additional diagnostics.
Despite the fact that specific numbers are indicated in the ultrasound report - limb length, volume, height and weight, you should not try to interpret them yourself. The limits of the norm indicators are large, borderline data do not necessarily indicate deviations, and the expectant mother needs to protect herself from stress.
At various stages of pregnancy, fetometry is regularly performed - this is the determination of the size of the fetus through ultrasound. The data obtained during the survey were subjected to statistical analysis over the years, and on their basis a table was compiled with weekly norm indicators.
It is the main parameter for a more accurate determination of the period and allows you to find out if there are any deviations in the intrauterine development of the baby. Knowing what it is, young parents themselves can, after an ultrasound examination, make sure that everything is in order.
Most often, ultrasound fetometry is performed either with a transvaginal sensor, or traditionally through the abdomen. In the first case, no preparation is required from the woman. A classic ultrasound will show more accurate results if you drink 500 ml of water an hour before the procedure and do not empty your bladder in the early stages. Filled, it will help improve visibility in the uterine cavity. After 12 weeks, this is no longer required, since this function will be performed by amniotic fluid.
The procedure is familiar to everyone: a special gel is applied to the stomach, and everything that happens in utero is displayed on a computer monitor. Modern programs allow you to automatically take measurements of the fetus, and the doctor then compares them with the general table of norms for weeks. This allows you to clarify the gestational age and timely identify pathologies in the development of the fetus.
Why is it called so? The term "fetometry" goes back to the Latin word "fetus" (translated as "offspring") and the Greek "metreo" (meaning "to measure, determine").
Norms and deviations
It is useful for parents to know what the norm is, according to the fetometry table, and when they talk about pathological abnormalities. Seeing a slight discrepancy between the true sizes and official figures, many begin to panic and draw the wrong conclusions, which in most cases turns out to be completely in vain.
- the data of the fetus fully correspond to the sizes in the table;
- they are less than 2 weeks behind or ahead of them (this period is acceptable for individual characteristics);
- the indicators are not on the same line, but scattered, but this difference is no more than 1 line: these discrepancies are permissible due to the spasmodic intrauterine development of the fetus.
Everything else is considered a deviation. It is especially dangerous when the fetometry of the fetus once again shows that the same size is more or less than the norm by 2 or even more lines.
For example, a growing head circumference may indicate, but to confirm the diagnosis, additional data obtained during dopplerometry and CTG, and observation in dynamics will be needed.
For comparison. If all dimensions of the fetus "fit" into the norm indicated in the fetometry table, except, for example, the length of the thigh, this is not at all an indicator of pathology. Perhaps the parents or other relatives of the child are simply the owners of very long (or, conversely, too short) legs.
In the presence of deviations, such serious diagnoses as "", "" are confirmed by two doctors: not only an obstetrician-gynecologist, but also a medical geneticist. They assess the genetic predisposition of the fetus and determine the causes of the identified pathology (chromosomal abnormalities, bad habits, parental age, intrauterine infection, etc.).
It is very important that the obstetrician-gynecologist is primarily involved in deciphering the obtained indicators: the ultrasound specialist only provides him with a summary sheet, which indicates what sizes and how much they differ from the norm of fetometry for a given gestational age. What parameters are taken into account during screenings?
Description of key indicators
To figure out what weekly fetal fetometry data are contained in the tables, you need to know the symbols for these parameters and their interpretation.
- BDP - biparietal size, the distance between the parietal bones, describes the development of the nervous system.
- DB - thigh length.
- DG - leg length.
- DN - the length of the nasal bone.
- DP - shoulder length.
- KTR - coccyx-parietal size.
- LZR - fronto-occipital size.
- OG - head circumference.
- OG (DHA) - chest volume (diameter of the chest).
- OC - abdominal circumference.
- PJ - transverse diameter of the abdomen.
- PYa - a fetal egg where the child develops.
- SJ - sagittal diameter of the abdomen (measured in the anterior-posterior direction).
- TVP - the thickness of the collar space.
This is the interpretation of the indicators that are most often indicated in the fetometry table. It may also include the lengths of other bones - more - and fibula, ulna, radius, as well as the foot. But they no longer have such significance for the detection of pathologies - they are used for comparison only as additional information.
Among other things, you can calculate the weight of the fetus by fetometry, carried out after the 20th week of pregnancy. All calculations are made automatically by the ultrasound machine itself based on the term, BPR, LZR, OZH, DB and OG. They give very accurate results and allow you to compare them according to the table with the norms.
I trimester
The first fetometry is prescribed at 12-13 weeks. Its purpose is to identify fetal malformations in early pregnancy.
This ultrasound screening does not identify a specific disease, but only points to markers that are typical for it. Based on the results obtained, additional studies may be prescribed. All suspicions that have arisen are confirmed or refuted by invasive laboratory techniques.
Some indicators of fetometry can be specified. For example, during the first screening, specialists use a table of average CTE values, since this size is very important for identifying abnormalities in the intrauterine development of the fetus.
Doctors include an increase in CTE by 1-2 weeks to the variants of the norm. If the pregnancy is not complicated by the Rh conflict, this may mean that the baby will be born a real hero and its weight will be more than 4 kg, and in some cases this may be an indication for carrying out.
These are the important data that the first fetometry gives into the hands of specialists.
About the timing. The first ultrasound screening is carried out during this period because of the TBP indicator. Until 11 weeks, it is so small that it cannot be measured. And after 14 weeks, this space is filled with lymph, which distorts the results of the study. It is this parameter that is a marker for most fetal chromosomal abnormalities.
II trimester
The time frame for the second ultrasound fetometry should be within the following timeframes:
- not earlier than 16 weeks;
- no later than 20;
- the best option is week 17, which, if abnormalities are detected, will allow more accurate additional genetic examinations;
- sometimes ultrasound is also performed at 21-22 weeks, but these are already the most extreme and undesirable terms.
The first ultrasound screening gives the most accurate results, but often even they are not enough to make a diagnosis. To do this, many indicators need to be seen in dynamics. Here it is just the data of the second fetometry that demonstrate it.
It performs the following tasks:
- identify defects that cannot be determined in the first trimester;
- confirm / refute the diagnosis previously made based on the results of the first screening;
- determine the risk level of suspects;
- detect deviations in the formation of a small organism.
Fetometry II trimester is assigned only to those women who, according to the results of the first ultrasound, were at risk.
Approximate norms of ultrasound at this stage of pregnancy are presented in the following tables.
Height Weight
Abdominal circumference
Head circumference
Calf length
Thigh length
Humerus length
Forearm bone length
If for some reason the timing of the second fetometry was shifted, you can use a table with averages from 21 to 27 weeks:
After examining the data of the second fetometry, the gynecologist can refer the woman for a consultation with a geneticist or independently prescribe invasive techniques to diagnose suspected pathologies. In cases where the diagnosis is still confirmed, a decision is made about the future of the pregnancy.
If therapeutic adjustment is not possible, artificial induction of labor is performed (for artificial labor, read in). If the detected pathology is reversible, treatment is prescribed as soon as possible in order to save the baby.
III trimester
The third fetometry can be prescribed on any day of the III trimester of pregnancy. The optimal period is 32-33 weeks. Since at this stage the matter is approaching childbirth, ultrasound is carried out more carefully than before.
For example, the baby's face is already perfectly visible, which makes it possible to identify such pathologies as the cleft palate or cleft lip. The doctor finds out how developed the fetus is in accordance with the gestational age.
It is usually not recommended to conduct such studies after 34 weeks. However, there are times when they are appointed immediately before the birth itself (at 37-38 weeks) in order to make the final decision on a caesarean section or.
Table of average values of the third fetometry of the fetus by week
If there are deviations at this stage, the woman is offered hospitalization. With the negative dynamics of the testimony received, doctors may decide to stimulate preterm labor.
Useful information. Everyone around (women, and often doctors themselves) like to talk about the importance of the first two fetometry and the optionality of the third. But after all, only she allows you to make the right decision on how to carry out the upcoming birth with minimal losses for mom and baby.
Information from the tables of fetometry of the fetus is for informational purposes only. It is not recommended for parents to draw any independent conclusions by comparing the results obtained with the norms, because they do not always reflect reality and require mandatory interpretation by specialists.
- The essence of the procedure
- Norms and deviations
- Description of key indicators
- I trimester
- II trimester
- III trimester
At various stages of pregnancy, fetometry is regularly performed - this is the determination of the size of the fetus through ultrasound. The data obtained during the survey were subjected to statistical analysis over the years, and on their basis a table was compiled with weekly norm indicators.
It is the main parameter for a more accurate determination of the period and allows you to find out if there are any deviations in the intrauterine development of the baby. Knowing what it is, young parents themselves can, after an ultrasound examination, make sure that everything is in order.
The essence of the procedure
Most often, ultrasound fetometry is performed either with a transvaginal sensor, or traditionally through the abdomen. In the first case, no preparation is required from the woman. A classic ultrasound will show more accurate results if you drink 500 ml of water an hour before the procedure and do not empty your bladder in the early stages. Filled, it will help improve visibility in the uterine cavity. After 12 weeks, this is no longer required, since this function will be performed by amniotic fluid.
The procedure is familiar to everyone: a special gel is applied to the stomach, and everything that happens in utero is displayed on a computer monitor. Modern programs allow you to automatically take measurements of the fetus, and the doctor then compares them with the general table of norms for weeks. This allows you to clarify the gestational age and timely identify pathologies in the development of the fetus.
Why is it called so? The term "fetometry" goes back to the Latin word "fetus" (translated as "offspring") and the Greek "metreo" (meaning "to measure, determine").
Norms and deviations
It is useful for parents to know what the norm is, according to the fetometry table, and when they talk about pathological abnormalities. Seeing a slight discrepancy between the true sizes and official figures, many begin to panic and draw the wrong conclusions, which in most cases turns out to be completely in vain.
- the data of the fetus fully correspond to the sizes in the table;
- they are less than 2 weeks behind or ahead of them (this period is acceptable for individual characteristics);
- the indicators are not on the same line, but scattered, but this difference is no more than 1 line: these discrepancies are permissible due to the spasmodic intrauterine development of the fetus.
Everything else is considered a deviation. It is especially dangerous when the fetometry of the fetus once again shows that the same size is more or less than the norm by 2 or even more lines.
For example, a growing head circumference may indicate hydrocephalus, but additional data obtained during dopplerometry and CTG, and follow-up will be needed to confirm the diagnosis.
For comparison. If all dimensions of the fetus "fit" into the norm indicated in the fetometry table, except, for example, the length of the thigh, this is not at all an indicator of pathology. Perhaps the parents or other relatives of the child are simply the owners of very long (or, conversely, too short) legs.
In the presence of deviations, such serious diagnoses as "intrauterine growth retardation", "hypotrophy" are confirmed by two doctors: not only an obstetrician-gynecologist, but also a medical geneticist. They assess the genetic predisposition of the fetus and determine the causes of the identified pathology (chromosomal abnormalities, bad habits, parental age, intrauterine infection, etc.).
It is very important that the obstetrician-gynecologist is primarily involved in deciphering the obtained indicators: the ultrasound specialist only provides him with a summary sheet, which indicates what sizes and how much they differ from the norm of fetometry for a given gestational age. What parameters are taken into account during screenings?
Description of key indicators
To figure out what weekly fetal fetometry data are contained in the tables, you need to know the symbols for these parameters and their interpretation.
- BDP - biparietal size, the distance between the parietal bones, describes the development of the nervous system.
- DB - thigh length.
- DG - leg length.
- DN - the length of the nasal bone.
- DP - shoulder length.
- KTR - coccyx-parietal size.
- LZR - fronto-occipital size.
- OG - head circumference.
- OG (DHA) - chest volume (diameter of the chest).
- OC - abdominal circumference.
- PJ - transverse diameter of the abdomen.
- PYa - a fetal egg where the child develops.
- SJ - sagittal diameter of the abdomen (measured in the anterior-posterior direction).
- TVP - the thickness of the collar space.
This is the interpretation of the indicators that are most often indicated in the fetometry table. It may also include the lengths of other bones - more - and fibula, ulna, radius, as well as the foot. But they no longer have such significance for the detection of pathologies - they are used for comparison only as additional information.
Among other things, you can calculate the weight of the fetus by fetometry, carried out after the 20th week of pregnancy. All calculations are made automatically by the ultrasound machine itself based on the term, BPR, LZR, OZH, DB and OG. They give very accurate results and allow you to compare them according to the table with the norms.
I trimester
The first fetometry is prescribed at 12-13 weeks. Its purpose is to identify fetal malformations in early pregnancy.
This ultrasound screening does not identify a specific disease, but only points to markers that are typical for it. Based on the results obtained, additional studies may be prescribed. All suspicions that have arisen are confirmed or refuted by invasive laboratory techniques.
Some indicators of fetometry can be specified. For example, during the first screening, specialists use a table of average CTE values, since this size is very important for identifying abnormalities in the intrauterine development of the fetus.
Doctors include an increase in CTE by 1-2 weeks to the variants of the norm. If the pregnancy is not complicated by the mother's diabetes mellitus and Rh conflict, this may mean that the baby will be born a real hero and its weight will be more than 4 kg, and in some cases this may be an indication for a caesarean section.
These are the important data that the first fetometry gives into the hands of specialists.
About the timing. The first ultrasound screening is carried out during this period because of the TBP indicator. Until 11 weeks, it is so small that it cannot be measured. And after 14 weeks, this space is filled with lymph, which distorts the results of the study. It is this parameter that is a marker for most fetal chromosomal abnormalities.
II trimester
The time frame for the second ultrasound fetometry should be within the following timeframes:
- not earlier than 16 weeks;
- no later than 20;
- the best option is week 17, which, if abnormalities are detected, will allow more accurate additional genetic examinations;
- sometimes ultrasound is also performed at 21-22 weeks, but these are already the most extreme and undesirable terms.
The first ultrasound screening gives the most accurate results, but often even they are not enough to make a diagnosis. To do this, many indicators need to be seen in dynamics. Here it is just the data of the second fetometry that demonstrate it.
It performs the following tasks:
- identify defects that cannot be determined in the first trimester;
- confirm / refute the diagnosis previously made based on the results of the first screening;
- determine the level of risk of suspected fetal pathologies;
- detect deviations in the formation of a small organism.
Fetometry II trimester is assigned only to those women who, according to the results of the first ultrasound, were at risk.
Approximate norms of ultrasound at this stage of pregnancy are presented in the following tables.
Height Weight
Abdominal circumference
Head circumference
Calf length
Thigh length
Humerus length
Forearm bone length
If for some reason the timing of the second fetometry was shifted, you can use a table with averages from 21 to 27 weeks:
After examining the data of the second fetometry, the gynecologist can refer the woman for a consultation with a geneticist or independently prescribe invasive techniques to diagnose suspected pathologies. In cases where the diagnosis is still confirmed, a decision is made about the future of the pregnancy.
If therapeutic adjustment is not possible, artificial induction of labor is performed (read about artificial labor in our article). If the detected pathology is reversible, treatment is prescribed as soon as possible in order to save the baby.
III trimester
The third fetometry can be prescribed on any day of the III trimester of pregnancy. The optimal period is 32-33 weeks. Since at this stage the matter is approaching childbirth, ultrasound is carried out more carefully than before.
For example, the baby's face is already perfectly visible, which makes it possible to identify such pathologies as the cleft palate or cleft lip. The doctor finds out how developed the fetus is in accordance with the gestational age.
It is usually not recommended to conduct such studies after 34 weeks. However, there are cases when they are appointed immediately before the birth itself (at 37-38 weeks) in order to make the final decision on a caesarean section or a natural birth of a baby.
Table of average values of the third fetometry of the fetus by week
If there are deviations at this stage, the woman is offered hospitalization. With the negative dynamics of the testimony received, doctors may decide to stimulate preterm labor.
Useful information. Everyone around (women, and often doctors themselves) like to talk about the importance of the first two fetometry and the optionality of the third. But after all, only she allows you to make the right decision on how to carry out the upcoming birth with minimal losses for mom and baby.
Information from the tables of fetometry of the fetus is for informational purposes only. It is not recommended for parents to draw any independent conclusions by comparing the results obtained with the norms, because they do not always reflect reality and require mandatory interpretation by specialists.
Throughout the nine months, every mother worries about the correct development of the baby. It is precisely to ensure full control over the development of the child in the womb and the timely detection of any abnormalities that pregnant women are strongly recommended to regularly visit the leading doctor in order to find out the size of the fetus by weeks of pregnancy.
Accurate diagnosis involves the use of ultrasound methods. Based on the results obtained, the specialist can determine how proportionally the baby develops, and whether the data obtained regarding growth and development correspond to the established norms.
What indicators are taken into account?
The key parameters that make it possible to determine the characteristics of the development of the fetus are indicators of its height and weight, but they begin to be measured only in the second part of the first trimester. Until that time, the dimensions of the embryo are so small that their measurement is extremely difficult.
According to medical indications, every pregnant woman is required to undergo at least three ultrasound examinations during all nine months. This number of procedures is considered minimal and can be increased by the decision of specialists, if there is a need to obtain additional information about the development of the fetus.
Periodic ultrasound is necessary for the timely detection of serious pathologies and the prevention of complications. As a rule, such studies are carried out no earlier than 10 and no later than 14 weeks, as well as in the second trimester in the period from 18 to 21 weeks.
To facilitate the task in medical practice, it is customary to measure the size of the fetus by weeks, because the fetal egg increases in volume almost daily.
The results of each ultrasound are recorded in protocols, from which information can be obtained regarding the symmetry of the development of the fetus, its growth rate and the compliance of indicators with established and used standards.
Throughout pregnancy, as the fetus develops, various parameters are taken into account. For example, up to 13 weeks, experts focus more on the analysis of the coccygeal-parietal length, measured from the coccyx to the parietal region of the fetus. This feature of the measurement is due to the fact that the fetus is in a bent position, so the opportunity to obtain the first data on growth appears no earlier than 14 weeks.
During the second scheduled ultrasound, specialists focus more on other indicators presented:
- fronto-occipital size or longitudinal line;
- circles of the skull, abdomen and chest;
- length of the lower and upper limbs.
An important factor indicating the normal development of the fetus is not only compliance with established standards, but also the symmetry of the measurements obtained.
Fetal size by week of pregnancy
The onset of pregnancy occurs by the end of the second week of the menstrual cycle, which is considered the moment of conception. The features of this process are known to everyone since school. Male ejaculation is accompanied by the release of millions of spermatozoa, only one of which, after entering the vagina and through the fallopian tubes, will be able to approach the egg.
During the third week, the formation of an embryonic vesicle occurs, inside which there is a large amount of fluid and cells. This bubble is so small that it is almost impossible to see it without special equipment. To be able to imagine the parameters of the bubble, compare it with a pea, the size of which does not exceed 0.2 mm in diameter.
From the beginning of the fourth week, the active development of the fetus begins, which almost doubles every week. So, by the end of the next week, the length of the fetal egg reaches 0.5 mm. Already at this stage, specialists have the first opportunity to obtain real data on the development of the fetus, which can be presented in the form of a table.
Table 1. Dimensions of the ovum from 1 to 13 weeks
|
Period |
Length indicators, mm |
Inner diameter, mm3 |
Area, mm2 | Volume, mm2 | Coccyx-parietal size, mm |
Yolk sac diameter, mm3 |
| Week 1 | - | - | - | - | - | - |
| 2 weeks | - | - | - | - | - | - |
| 3 week | 0,2 | - | - | - | - | - |
| 4 week | 0,5 | - | - | - | - | - |
| 5 week | 1,5 | 18 | 245 | 2 187 | 3 | - |
| 6 week | 4 | 22 | 363 | 3 993 | 6 | 3 |
| 7 week | 7 | 22 | 432 | 6 912 | 10 | 4 |
| 8 week | 10 | 30 | 675 | 13 490 | 16 | 4,5 |
| 9 week | 15 | 33 | 972 | 16 380 | 23 | 5 |
| 10 week | 31 | 39 | 1 210 | 31 870 | 31 | 5,1 |
| 11 week | 55 | 47 | 1 728 | 55 290 | 41 | 5,5 |
| 12 week | 80 | 56 | 2 350 | 87 808 | 53 | 6 |
| 13 week | 105 | 65 | 3 072 | 131 070 | 66 | 6 |
The lengths given in the table are measured from the crown of the head to the coccyx and are averaged. According to experts, due to the distinctive features of development, slight deviations from the given average indicators are allowed. A significant deviation, as well as a violation of the permissible proportions between the indicators, which is an important factor, is a prerequisite for further research.
By the end of the eighth week, the length of the fetal egg reaches 11 mm. According to numerous studies, the weight of the fetus at this stage does not exceed 1.5 grams. Over the next week, there is an increase in weight by another 0.5 g, and by the end of the tenth week, it can reach 4 g.
At the eleventh, through ultrasound, it becomes possible to obtain the first data on the length of the thigh and chest, which are respectively 7 and 20 mm. By this period, the weight of the fetus reaches 11 g. By the end of 12 weeks, the diameter of the chest will reach 24 mm, and the diameter of the thigh - 9 mm.
From the 11th to the 40th week, specialists carefully examine not only the general length indicators, but also the parameters of individual parts of the body, which allows you to get a general and complete picture of the correct development of the fetus.
Starting from the thirteenth, during examinations, measurements of the baby’s skull are also taken into account, whose weight by this time reaches 30 g.
Table 2. Sizes of the fetal egg by week: from the 13th to the 40th
| Period | Length indicators, mm | Thigh length, mm | Chest diameter, mm | Skull perimeter, mm | Skull area, mm2 |
| 11 week | 55 | 7 | 20 | - | - |
| 12 week | 80 | 9 | 24 | - | - |
| 13 week | 105 | 12 | 25 | - | - |
| 14 week | 110 | 16 | 26 | 80 | 510 |
| 15 week | 115 | 19 | 28 | 90 | 675 |
| 16 week | 160 | 22 | 34 | 102 | 860 |
| 17 week | 170 | 24 | 38 | 120 | 1 080 |
| 18 week | 205 | 28 | 41 | 126 | 1 320 |
| 19 week | 215 | 31 | 44 | 138 | 1 450 |
| 20 week | 250 | 34 | 48 | 144 | 1 730 |
| 21 weeks | 260 | 37 | 50 | 151 | 1 875 |
| 22 week | 270 | 40 | 53 | 162 | 2 190 |
| 23 week | 385 | 43 | 56 | 173 | 2 520 |
| 24 week | 300 | 46 | 59 | 183 | 2 710 |
| 25 week | 310 | 48 | 62 | 194 | 3 072 |
| 26 week | 325 | 51 | 64 | 199 | 3 260 |
| 27 week | 340 | 53 | 69 | 215 | 3 675 |
| 28 week | 350 | 55 | 73 | 218 | 3 880 |
| 29 week | 365 | 57 | 76 | 225 | 4 170 |
| 30 week | 375 | 59 | 79 | 234 | 4 563 |
| 31 weeks | 385 | 61 | 81 | 240 | 4 810 |
| 32 week | 400 | 63 | 83 | 246 | 5 040 |
| 33 week | 410 | 65 | 85 | 255 | 5 290 |
| 34 week | 420 | 66 | 88 | 264 | 5 547 |
| 35 week | 450 | 67 | 91 | 270 | 5 810 |
| 36 week | 455 | 69 | 94 | 272 | 6 075 |
| 37 week | 480 | 71 | 97 | 276 | 6 348 |
| 38 week | 485 | 71 | 97 | 282 | 6 620 |
| 39 week | 490 | 73 | 99 | 285 | 6 684 |
| 40 week | 500 | 75 | 101 | 290 | 6 768 |
Biparental fetal size by week
Another important indicator that experts take into account in their studies is the biparietal size, represented by the distance between the outer surface of the upper contour and the inner region of the lower contour between the parietal bones.
As in the case of other indicators, minor deviations from the norm are allowed when analyzing the obtained biparietal size. If the established data is exceeded, the specialist must evaluate other parameters, represented by the circumference of the abdomen, the length of the limbs.
The analysis of this indicator is extremely important, because its deviations from the norm in many cases may indicate serious pathologies, represented by hernias, tumors and other volumetric formations, in which the only way out may be termination of pregnancy. The insufficient development of the baby's head or a decrease in its size is also considered undesirable, which may be due to the underdevelopment or absence of the anatomical structures of the brain. In this case, experts also strongly recommend termination of pregnancy.
Often in the third trimester, reduced indicators of BDP are diagnosed, which, if detected in a timely manner, can be successfully corrected.
As a rule, in this case, a diagnosis of intrauterine growth retardation is made, and the pregnant woman is prescribed treatment with drugs that help improve uteroplacental blood flow and ensure the transport of essential nutrients.
In medical practice, the following average indicators of the biparietal size of the fetus are used:
- 8 week - 6 mm;
- 9 week - 8.5;
- 10 week - 11 mm;
- 11 weeks - 15 mm;
- 12 weeks - 20 mm;
- 13 week - 24 mm;
- 14 weeks - 26 mm;
- 15 week - 32 mm;
- 16 weeks - 35 mm;
- 17 week - 39 mm;
- 18 weeks - 42 mm;
- 19 week - 44 mm;
- 20 week - 47 mm;
- 21 weeks - 51 mm;
- 22 weeks - 54 mm;
- 23 weeks - 58 mm;
- 24 weeks - 61 mm;
- 25 week - 64 mm;
- 26 weeks - 67 mm;
- 27 week - 69 mm;
- 28 weeks - 72 mm;
- 29 week - 75 mm;
- 30 week - 78 mm;
- 31 weeks - 80 mm;
- 32 weeks - 82 mm;
- 33 weeks - 84 mm;
- 34 weeks - 86 mm;
- 35 week - 88 mm;
- 36 week - 90 mm;
- 37 week - 91 mm;
- 38 weeks - 92 mm;
- 39 week - 94 mm;
- 40 weeks - 95 mm.
Weight indicators
Of course, it is not possible to establish the exact weight of the fetus by means of an ultrasound examination, so experts are guided by other sizes and established norms. For the first time, the weight of the fetus is indicated on the eighth week, from which it becomes possible to obtain the first necessary data.
Table 3. Fetal weight by week
| Period | Weight indicators, g |
| 8 week | 1 |
| 9 week | 2 |
| 10 week | 4 |
| 11 week | 7 |
| 12 week | 14 |
| 13 week | 23 |
| 14 week | 43 |
| 15 week | 70 |
| 16 week | 100 |
| 17 week | 140 |
| 18 week | 190 |
| 19 week | 240 |
| 20 week | 300 |
| 21 weeks | 360 |
| 22 week | 430 |
| 23 week | 501 |
| 24 week | 600 |
| 25 week | 660 |
| 26 week | 760 |
| 27 week | 875 |
| 28 week | 1005 |
| 29 week | 1153 |
| 30 week | 1319 |
| 31 weeks | 1502 |
| 32 week | 1702 |
| 33 week | 1918 |
| 34 week | 2146 |
| 35 week | 2383 |
| 36 week | 2622 |
| 37 week | 2859 |
| 38 week | 3083 |
| 39 week | 3288 |
| 40 week | 3462 |
As a rule, from the data obtained after an ultrasound examination, it is not easy for many women to understand how large the fetus is at this stage. To facilitate this task, the size of the fetal egg by week can be compared with well-known objects. As already noted, the first indicators of the length of the fetus can be obtained only in the third week, when its diameter is 0.2 mm. It is extremely difficult to examine the fetus at this time, and it can only be compared with a poppy seed.
By the end of the fourth week, the fruit almost doubles in size and now it can be safely compared with sesame seeds in size. By the end of the fifth, the fetal egg acquires dimensions comparable to sunflower seeds.
Do you know which bird is considered the smallest on the planet? These are hummingbirds, whose sizes rarely exceed 5.7 centimeters, and their weight is in the range from 1.6 to 2 g. It is with the egg of this bird that a human fetus can be compared in size in the sixth week of its development. By the end of the seventh, its size is comparable to the parameters of an ordinary bean.
On the eighth fruit, in terms of parameters, it can be compared with an unripe olive, and by the end of the ninth - with a large grape.
At the tenth week, the fetus reaches the size of a candy, which doctors do not recommend for pregnant women to lean on. The fruit reaches the size of an apricot by the end of the next period, used as a unit of measurement. At the 12th week, the fruit can be compared with a pea pod, and by the end of the thirteenth - with a ripe fig.
Over the next 7 days, the fruit will grow to the size of a medium pear, and after another week - to the size of an avocado. The average weight of newborn kittens is about 100 g. This is how much a human fetus weighs at the 16th week of its development, and in length it can be compared with an average carrot.
At week 17, the fruit can be compared with a medium potato, and at the end of the eighteenth, with a large tomato.
Imagine a big banana in your hands. It is these sizes that the baby reaches by the end of the nineteenth period. At the 20th week, it can be compared to a small hare. Have you seen such an exotic fruit as Thai mango? At 21 weeks, the weight of the fetus can be compared with it.
Among the penguins, the largest and heaviest are representatives of the Imperial species, whose height often reaches 125 cm, and their weight is 50 kg. Eggs of emperor penguins weigh up to 450 g. This is how much a human fetus weighs at 22 weeks of its development.
At week 23, it can be compared in terms of length to a corncob, and by the end of week 24, it can be compared to the weight of a green coconut. By the end of the next period, the size of the baby in the womb can be compared with newborn polar bear cubs, which, despite the impressive volume of adults, are born quite small.
By the end of the 26th week, the baby's weight can be compared with an average head of broccoli, and by the 27th - with a pomelo fruit.
If we take for comparison the length of the baby from the heels to the crown, then at 28 weeks it is comparable to the growth of a newborn tiger cub. The largest bird on the planet is the African ostrich, which can grow up to 200 centimeters and weigh 120 kg. The eggs of these birds weigh an average of 1,200 g. It is this weight that is considered the norm for a baby at the 29th week of its development.
By the end of the next period, the child is comparable to the weight of a six-month-old kitten, and by the end of 31 weeks - to the weight of a newborn lion cub.
In terms of growth, a baby at 32 weeks can be compared with a small blue penguin, and by the end of the next period, it reaches the weight of an average pineapple. At week 34, the baby acquires the size of a ripe melon of medium parameters.
After the next seven days, the weight of the baby becomes comparable to the weight of a small pumpkin, and after another 14 days - to the size of a watermelon.
By the end of the thirty-ninth week, the baby's length indicators reach 50 cm. It is with such length indicators that dolphins are born. By the end of the 40th week, the baby can already be safely compared with the average newborn who is ready to meet the world.
Take care of your health and future offspring. Good luck with your birth and good health.
- home
- Surveys
- Ultrasound norms
Ultrasound, or Ultrasound- This is a survey method that is widely used during pregnancy at any time. This diagnostic study is relatively simple, highly informative and safe for both mother and child. The main tasks of ultrasound during pregnancy are:
- Confirmation of the fact of pregnancy;
- Measurement of the size and weight of the fetus, the correspondence of these data to the gestational age;
- Assessment of fetal viability;
- Determination of anomalies in the development of the fetus;
- Determining the size of the placenta, its degree of maturity and the place of attachment;
- Determination of the quantity and quality of amniotic fluid (amniotic fluid);
- Determination of the sex of the child.
An ultrasound scan during pregnancy is screening method surveys, i.e. it is mandatory for every pregnant woman. According to the order of the Ministry of Health of the Russian Federation No. 457 “On improving prenatal diagnosis in the prevention of hereditary and congenital diseases in children”, a three-time screening ultrasound was approved:
- the first ultrasound is performed in terms of 10 to 14 weeks;
- the second - from 20 to 24 weeks;
- the third - from 32 to 34 weeks.
It is important to know that problems may arise at any time, due to which the doctor will prescribe additional ultrasound.
The most common reasons for this are:
- Drawing pains in the lower abdomen;
- The appearance of bloody discharge from the vagina;
- Mismatch between the size of the fetus and the gestational age;
- Anomalies of attachment of the placenta;
- Multiple pregnancy;
- Incorrect position of the fetus.
Can be used for ultrasound two types of sensors: vaginal (examination is carried out through the vagina) and abdominal (the emitter is applied to the abdomen through a small layer of a special gel). During an abdominal ultrasound, a woman should prepare: drink at least 1-1.5 liters of fluid 1 hour before the procedure to fill the bladder. When using a vaginal probe, no special preparation is needed; in this case, the bladder, on the contrary, must be emptied.
information As a rule, the doctor begins the examination in the abdominal way. If the fetus is poorly visualized, which often happens in the first trimester, then they proceed to a vaginal ultrasound.
Most pregnant women during the study are concerned about the duration of pregnancy and the expected date of delivery. In this case, ultrasound can give the most accurate data when carried out in the early stages (up to 12 weeks), then various factors can influence the result, primarily the size of the fetus itself.
Below is a table of fetal length and weight for each week of pregnancy, but keep in mind that these are only averages and your baby may differ from these readings.
Fetal size chart by week
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Pregnancy period, weeks |
Weight, g |
Length cm |
The following tables provide data on fetal biometrics that are measured at each ultrasound. They are presented in the 10th, 50th and 95th percentiles. Most often, they are guided by the 50th percentile, and the rest are considered normal fluctuations.
Dimensions of the fetal head by week of pregnancy
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Pregnancy period, weeks |
Fronto-occipital size (LZR), mm |
Biparietal size (BPR), mm |
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Circumference of the abdomen and fetal head
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Pregnancy period, weeks |
Abdominal circumference, mm |
Head circumference, mm |
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The length of the bones of the lower leg and femur of the fetus
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Pregnancy period, weeks |
Lower leg bones, mm |
Femur, mm |
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The length of the humerus and bones of the forearms of the fetus
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Pregnancy period, weeks |
Forearm bone length, mm |
Humerus length, mm |
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Norms at the first ultrasound at 10-14 weeks
The first screening ultrasound is performed for a period of 10-14 weeks. Its main tasks are:
- The study of the thickness of the collar zone(the area between the soft tissues covering the spine and the inner surface of the skin, filled with fluid). Evaluation of the size of the neck crease is very important, because. is a fairly accurate way of timely diagnosis of various chromosomal diseases, in particular Down syndrome. In the presence of an enlarged collar space, the doctor should refer the pregnant woman for a consultation with a geneticist. A woman is assigned additional examination methods: a blood test for alpha-fetoprotein and chorionic gonadotropin, invasive diagnostic methods (amniocentesis - the study of amniotic fluid, placentocentesis - the study of placental cells, cordocentesis - the study of blood taken from the umbilical cord of the fetus).
Normal values of the collar space (NTP) in the first trimester of pregnancy
- Measurement of the coccygeal-parietal size (KTR). This is an important indicator by which you can determine the size of the fetus and the approximate gestational age.
Values of the coccygeal-parietal size by gestational age
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Pregnancy period, weeks |
KTR percentile values, mm |
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Important
- The study of fetal cardiac activity. The fetal heartbeat is the main indicator of its viability.
Normal heart contractions should occur at regular intervals, i.e. be rhythmic. Arrhythmia may indicate the presence of congenital heart disease or fetal hypoxia. The heartbeat should sound very clear and distinct; in the presence of deaf tones, intrauterine oxygen deficiency can be suspected. An important indicator is the heart rate.
Normal heart rate by gestational age
Tachycardia is an increase in the number of heartbeats more than normal, bradycardia is a decrease in heart rate to 120 beats per minute or less. Most often, such changes in the heartbeat occur during fetal hypoxia as a reaction to a decrease in oxygen in the blood. In such cases, the pregnant woman must be prescribed treatment, which is often carried out in a hospital. A therapy is prescribed aimed at improving uteroplacental blood flow, improving intracellular metabolism.
- Evaluation of the development and presence of various organs(bladder, kidneys, liver, stomach, heart), spine, and upper and lower extremities of the fetus. If anomalies in the development of organs are detected, a woman is sent to a genetic consultation. After a detailed examination, a geneticist decides on the viability of the child and the possible termination of pregnancy.
Normal second ultrasound at 20-24 weeks
The doctor prescribes the second planned ultrasound at 20-24 weeks. At this time, the following are investigated:
- Biometric indicators(biparietal size, fronto-occipital size, length of tubular bones, abdominal and head circumference). These indicators are measured to assess the growth of the fetus and its appropriate size for the gestational age.
- Identification of various fetal malformations. It is in this period that the diagnosis will be the most informative, because. at the first examination, the child is still too small, and at the third planned ultrasound it will already be too large, in addition, the placenta may interfere with a thorough examination if it is located on the anterior wall of the uterus.
- Structure, thickness, location and maturity of the placenta. This is the most important organ that supplies the fetus with all the nutrients necessary for its normal development.
Normal thickness of the placenta depending on the gestational age
|
Pregnancy period, weeks |
Permissible fluctuations |
Normal values, mm |
With an increase in the thickness of the placenta, the doctor may suggest the presence of placentitis (inflammation of the placenta). Making such a diagnosis requires an additional examination for the presence of infection and subsequent treatment in a hospital.
Ultrasound also evaluates maturity of the placenta. This is an important indicator that characterizes the ability of the "children's place" (synonymous with the term "placenta") to provide the fetus with the necessary substances.
Degrees of maturity of the placenta
Late maturation of the placenta is quite rare and is mainly caused by:
- smoking mother,
- She has various chronic diseases.
Premature maturation of the placenta occurs more frequently. The reasons for this condition are:
- Smoking,
- Endocrine diseases of the mother (in particular, diabetes mellitus),
- intrauterine infections,
- gestoses,
- A history of abortion.
When making such diagnoses, a pregnant woman is prescribed an examination: dopplerometry, CTG, tests for possible infections. In the future, the woman must undergo a course of treatment. Prescribed drugs for the treatment of fetal hypoxia, vitamin therapy, antispasmodics to reduce the tone of the uterus, in the presence of infection - antibiotic therapy.
An equally important task for the doctor of ultrasound diagnostics is to study places of attachment of the placenta. Most often, the "children's place" is attached to the back wall of the uterus, less often - to the front, and even less often - in the bottom area. Normally, the placenta should be 6 cm or more away from the internal os of the cervix.
If it is located below and overlaps the internal os of the uterus, they speak of placenta previa. This is a serious type of obstetric pathology that threatens the life and health of a woman and a child. Often this anomaly occurs in multiparous women, after inflammatory diseases of the uterus, uterine myoma, after abortions. A pregnant woman is carefully observed in a hospital or at home, where she must observe complete rest and refrain from sexual activity. In the event of bleeding, immediate hospitalization is required.
Quantity and quality of amniotic fluid
Mean Normal Amniotic Fluid Index
|
Pregnancy period, weeks |
Possible fluctuations |
Average |
When the amount of amniotic fluid changes in one direction or another, they speak of polyhydramnios and oligohydramnios.
Polyhydramnios often occurs in women with infectious diseases, diabetes mellitus, multiple pregnancies, some fetal malformations, Rh sensitization (incompatibility of the blood of the mother and fetus according to the Rh factor). The condition requires mandatory treatment: antibiotic therapy, drugs that improve uteroplacental blood flow.
Oligohydramnios is a pathological decrease in the amount of amniotic fluid less than 500 ml. The causes of this condition are still unknown. If there is very little water, this may indicate a severe malformation of the fetus: the complete absence of kidneys. There is practically no treatment for oligohydramnios, all therapy is aimed at supporting the child.
The ultrasound specialist also evaluates amniotic fluid quality. Normally, they should be transparent. If there is turbidity, mucus, flakes in the amniotic fluid, there is a suspicion of an infectious process. A woman is tested for hidden infections and is being treated.
- Cord evaluation. Ultrasound examination can detect the entanglement of the umbilical cord around the cervix of the fetus. But in the second trimester of pregnancy, it does not cause alarm. The baby is in constant motion, and the umbilical cord can unwind.
- Cervical assessment. Normally, the neck should be at least 3 cm, and only closer to childbirth does it begin to shorten and smooth out. The internal os must be completely closed. Shortening of the neck or opening of the pharynx is a sign of isthmic-cervical insufficiency. A woman should have stitches in her cervix or an obstetric pessary (a mechanical device in the form of several rings that is inserted into the vagina and protects the cervix from premature opening).
Third ultrasound at 32-34 weeks
The third planned ultrasound is carried out for a period of 32-34 weeks. Its tasks are:
- Determining the position and presentation of the fetus. At this time, the child is already quite large and its mobility is limited. The position in which he is during the ultrasound will remain until the end of the birth. The definition of these indicators is important for resolving the issue of the method of delivery. Allocate longitudinal, transverse and oblique position of the fetus. With a longitudinal arrangement of the child, a woman can give birth naturally, the transverse and oblique position are a relative indication for a caesarean section. Natural childbirth is also possible with a normal cephalic presentation of the fetus, the pelvic location is an indication for operative delivery.
- Assessment of the size and weight of the fetus. These indicators help to understand how the child develops. If the size of the fetus is behind the average, you can suspect a delay in intrauterine development of the child. Determination of fetal malnutrition requires the start of treatment for a pregnant woman. If the fetus, on the contrary, is ahead of the indicators, then we can talk about a large fetus. Probably the birth of a child with a large weight (more than 4 kg). This can significantly complicate childbirth, so a woman is often offered an operative delivery.
- The study of the placenta, its size, degree of maturity and place of attachment. Migration of the placenta in this period has already been completed, it will occupy the same position for childbirth. It should be borne in mind that with full presentation, childbirth is possible only by caesarean section. With a low location of the child's place, the birth of a child through the natural birth canal is possible, but this is fraught with a high risk of bleeding during childbirth.
- Assessment of the quantity and quality of amniotic fluid(See topic: normal values for the second planned ultrasound at 20-24 weeks).
The norm of ultrasound before childbirth
Ultrasound examination before childbirth is not mandatory for all pregnant women and is carried out selectively according to indications. Its main task is to resolve the issue of the method of delivery. During an ultrasound, the following is determined:
- Position and presentation of the child;
- Estimated fetal weight at birth;
- The position of the umbilical cord to exclude entanglement.
Fetometry of the fetus is a method for determining the size of the anatomical structures of the unborn baby using ultrasound. Diagnostic data is checked against normative indicators to find out whether the baby is developing correctly in the womb.
Routine ultrasound examinations are performed three times: at 12, 20, and 32 weeks. The normal course of pregnancy gives reason to carry out fetometric diagnostics in the same period.
The procedure is carried out in two ways:
- transvaginally - a vaginal probe is inserted into the vagina.
- transabdominally - the contents of the uterus are examined through the outer abdominal wall.
During the examination, the doctor takes measurements of the fetal organs on the monitor screen, then makes a diagnosis about the correct development and formation of individual organs.
Additionally, fetometric analysis is usually carried out in such cases:
- the mother's condition causes concern to the gynecologist;
- there is a suspicion of a violation of intrauterine development of the fetus.
Key points of the fetometric study
The key data of the fetometric study are the following indicators:
- DB - thigh length;
- BPR - biparietal size;
- DP - shoulder length;
- KTR - coccyx-parietal size;
- DN - the length of the nasal bone;
- LZR - fronto-occipital size;
- OG - head circumference;
- DG - leg length;
- OC - abdominal circumference;
- TVP - the thickness of the collar space.
The decoding of the designations of the studied parameters is provided, since the fetometric data are written in the table in Latin.
A video about the stages of ultrasound was presented by the 1st Medical Quarter of Crede Experto on Taganka.
Baby weight
The body weight of the child by the 12th week is normally only 19 g, by the middle of pregnancy the baby will weigh about 345 g, and by the 32nd week - almost 2 kg.
If timely attention is paid to the problem with the discrepancy between the body weight of the fetus to the standard, and preventive measures are taken, then it will be relatively easy to correct the situation. The rate of weight gain is greatly influenced by the genetic factor. The gynecologist makes sure that the dynamics are positive.
KTP (CRL, coccyx-parietal size)
KTP (the Latin analogue of CRL) means the coccygeal-parietal size, that is, the growth of the child. It is calculated from the crown of the head to the end of the coccyx.
If this indicator slightly differs from the norm, then the fetus is not in danger. An increase in CTE over several weeks by the same value indicates that the fetus is relatively large.
BDP (BPD, biparietal and fronto-occipital head sizes)
The letters BPD denote the width of the fetal head. This is the maximum distance between the parietal bones. Size can be determined by taking measurements along the smallest axis of the circle between the temples of the child. BDP allows you to set the exact gestational age.
The parameter of the biparietal size of the fetal head (BDP) helps to identify developmental abnormalities already during the first trimester. The data obtained characterize the state of the fetal nervous system.
LZR or fronto-occipital size is calculated between the most distant points of the forehead and the back of the head.
OG (chest circumference)
The volume of the child's chest is determined by calculating the diameter of its circumference. A size that does not correspond to the norm should not cause much concern; most likely, this is a genetic feature. Perhaps the baby will just be born large. It is necessary to take into account the physical data of the mother and father.
OC (abdominal circumference)
Abdominal circumference is measured at 20 and 32 weeks of pregnancy. The parameter is calculated along the lines of the liver, stomach and umbilical vein. When the difference in indicators exceeds the permissible norm, the doctor will diagnose intrauterine growth retardation. However, to confirm it, the size of the coolant is calculated in relation to other parameters - the size of the head, thigh, BDP. If most of the indicators are normal, then this indicates a delay in the development of an asymmetric form.
DB (thigh length)
If a discrepancy is found in the indicator of the length of the thigh, then this also does not indicate the presence of pathology. Much depends on individual characteristics. For example, when the duration of the thigh and tibia is greater than normal, it means that the parents of the unborn baby or other relatives have a long leg.
PMP (PVP)
PVP is the estimated body weight of the fetus. During an ultrasound examination, there is a possibility of an error in weight. To eliminate the error, this figure is calculated using various medical formulas.
Calculation methods:
- Zhordania (Lebedeva) - PMP \u003d standing height of the fundus of the uterus × abdominal circumference.
- Bublichenko - PMP \u003d 1/20 of the woman's weight.
- Lankovitsa - PMP \u003d (height + weight of the mother + abdominal circumference + height of the fundus of the uterus) × 10.
- Jones - PMP \u003d (height of the fundus of the uterus - 11) × 155. The value of 11 is a conditional coefficient for a pregnant woman weighing up to 90 kg.
- Yakubova - PMP \u003d (abdominal circumference + uterus standing height) × 100/4.
Calculations are made after 38 weeks of pregnancy.
The Family TV channel presented a video about an ultrasound scan in the third trimester.
Norms of fetometry of the fetus by week
Table of approximate norms of fetal development by week.
| Gestational age | Weight, g | CTE, cm | OG (GDK), mm | dB, mm | BPR, mm |
| 11 | 11 | 6,8 | 20 | 7 | 18 |
| 12 | 19 | 8,2 | 24 | 9 | 21 |
| 13 | 31 | 10,0 | 24 | 12 | 24 |
| 14 | 52 | 12,3 | 26 | 16 | 28 |
| 15 | 77 | 14,2 | 28 | 19 | 32 |
| 16 | 118 | 16,4 | 34 | 22 | 35 |
| 17 | 160 | 18,0 | 38 | 24 | 39 |
| 18 | 217 | 20,3 | 41 | 28 | 42 |
| 19 | 270 | 22,1 | 44 | 31 | 44 |
| 20 | 345 | 24,1 | 48 | 34 | 47 |
| 21 | 416 | 25,9 | 50 | 37 | 50 |
| 22 | 506 | 27,8 | 53 | 40 | 53 |
| 23 | 607 | 29,7 | 56 | 43 | 56 |
| 24 | 733 | 31,2 | 59 | 46 | 60 |
| 25 | 844 | 32,4 | 62 | 48 | 63 |
| 26 | 969 | 33,9 | 64 | 51 | 66 |
| 27 | 1135 | 35,5 | 69 | 53 | 69 |
| 28 | 1319 | 37,2 | 73 | 55 | 73 |
| 29 | 1482 | 38,6 | 76 | 57 | 76 |
| 30 | 1636 | 39,9 | 79 | 59 | 78 |
| 31 | 1779 | 41,1 | 81 | 61 | 80 |
| 32 | 1930 | 42,3 | 83 | 63 | 82 |
| 33 | 2088 | 43,6 | 85 | 65 | 84 |
| 34 | 2248 | 44,5 | 88 | 66 | 86 |
| 35 | 2414 | 45,4 | 91 | 67 | 88 |
| 36 | 2612 | 46,6 | 94 | 69 | 89,5 |
| 37 | 2820 | 47,9 | 97 | 71 | 91 |
| 38 | 2992 | 49,0 | 99 | 73 | 92 |
| 39 | 3170 | 50,2 | 101 | 75 | 93 |
| 40 | 3373 | 51,3 | 103 | 77 | 94,5 |
Tables of norms were created on the basis of world average data on pregnancy and fetal development.
The role of fetometry in assessing fetal development
The parameters and dimensions of the fetus obtained during the fetometric analysis allow the doctor to more accurately determine:
- child health (for example, intrauterine growth retardation);
- mother's condition;
- date and outcome of the upcoming birth.
By changing the size of individual organs, the development of syndromes can be detected:
- Down;
- Patau;
- Edwards;
- Smith-Lemli-Opitz;
- Miller-Dikker;
- Williams;
- Angelman.
Is it possible to calculate the height and weight of the child according to the results of ultrasound?
The height and weight of the embryo is determined by first knowing the following indicators:
- obstetric gestational age;
- head size (BPR, LZR, OG);
- the length of the femur;
- the size of the circumference of the abdomen and chest.
Calculator for calculating the height and weight of a child
The size of the fetus by weeks (weight and height) are very important indicators by which the doctor evaluates the development of the unborn baby. Why is this data so important? How are fetal measurements taken during pregnancy?
Throughout the pregnancy, doctors measure the size of the fetus and its weight. These measures are necessary in order to early recognition of developmental disabilities, and they also help determine the expected date of delivery. Regular monitoring of these indications will allow you to recognize in time.
How the baby will be born will depend on the weight of the baby. If the baby is very large, the likelihood of a caesarean section is high. If the baby is too small, doctors will be ready to give him first aid immediately after birth, if necessary.
Norms of fetal weight by week of pregnancy
Weight is an important indicator of a baby's development. The calculation of the weight of the fetus begin to do using ultrasound only at 8 weeks of gestation, since before this period the fetus is still very small. The baby quickly gains weight in the first and third trimesters.
Here are the tables of the normal weight of the fetus by week of pregnancy, which indicate the average weight starting from the 8th week:
First trimester
| 1 gram | 3 grams | 4 grams | 7 grams | 14 grams | 23 grams |
Second trimester
| 43 grams | 70 grams | 100g | 140 grams | 190 grams | 240 grams | 300 grams |
Fetal measurements, or fetometry, are carried out using (abbreviated as ultrasound). It is done in two ways: vaginal (using a special sensor that is inserted into the vagina) or abdominal (the doctor applies the sensor to the skin of the abdomen).
In the first trimester the ultrasound specialist pays attention only to three indicators of the size of the embryo:
- PJ (fetal egg) - the size of the cavity where the fetus develops (it is here that the placenta will appear a little later);
- BDP (biparietal distance) - the distance between the left and right temporal bones;
- KTP (coccyx-parietal size) - the distance from the top of the head to the coccyx.
Table showing the normal (average) readings of PU, BDP and CTE in the embryo from 5 to 13 weeks of development:
In the second and third trimester study the following indicators:
- fetal growth;
- DB (femur length);
- BDP (biparietal size of the fetal head);
- DHA (chest diameter);
- other indications: OB (girth or circumference of the abdomen), LZR (distance between the back of the head and forehead), DP (length of the shoulder bone).
Table showing normal (average) readings in the fetus from 11 to 40 weeks of development:
Deviations from the norm
Each child develops in leaps and bounds, so a small difference from the average is not considered a serious deviation. During pregnancy, the doctor takes measurements of the size of the fetus several times. Pathology can be considered a significant difference from the average value of several indicators at once. In this case, fetometry is carried out several times in a row.
Increase or decrease in fetal weight
Small fruit weight can be considered both the norm (if the child's parents are not large), and a deviation. In the second case, there are several reasons:
- bad habits of the future mother (drinking alcohol, smoking);
- the use of antibiotics;
With poor weight gain in a child, the mother should give up bad habits, stop antibiotic treatment and start eating well.
Overweight fetus, may be a consequence of the presence in the mother's diet of fatty and other unhealthy foods. Refusal of the same products will be the solution to the problem. In some cases, a large fetal weight is observed in women suffering.
Increase or decrease in CTE (coccygeal-parietal size)
KTP is an indicator by which the size of the fetus is determined for up to 13 weeks. His rapid growth may indicate that in the future the embryo will be very large (up to 4 kg or more). In this case, a woman is not recommended to use multivitamins and drugs that speed up metabolism.
If this indicator hardly increases, this may indicate the following deviations from the norm:
- hormonal deficiency (a woman is prescribed hormonal drugs or);
- infections (in this case, the woman must undergo an additional examination, after which the doctor will prescribe treatment);
- genetic disorders of development: Down's syndrome, etc.;
- diseases of the internal organs of a woman;
- death of the embryo (in this case, the woman needs to provide emergency care and remove the dead fetus from the uterus).
Increase or decrease in BDP (biparietal size of the fetal head)
Shift in the BDP indicator to a greater side speaks of hydrocephalus or dropsy (an increase in the head of the embryo). This deviation can cause fetal death (if fluid accumulates in the brain cavity).
Downward shift in BDP indicates that the baby's head is reduced. This is due to developmental delay. If not only BDP decreases, but also other indicators, there is a risk that the child will have numerous congenital malformations after the appearance.
In order to prevent the development of many pathological abnormalities of the fetus, a woman needs observe the following preventive measures:
- (only on the recommendation of a doctor);
- stopping the use of alcoholic beverages;
- giving up cigarettes and drugs;
- treatment of infections affecting the embryo;
- stop contact with toxic substances and heavy metals.
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