How to find out the approximate weight of the fetus. Estimated fetal weight based on formulas and ultrasound data. What affects fetal weight

Expectant mothers are always very interested in what weight their baby will be born with. Therefore, they are keenly interested in how much the baby weighs while still in the womb. This question is also important for doctors. Although the weight of the fetus is called estimated, even it allows you to learn a lot about the development of the baby. What is the usual weight of a baby in the mother’s womb during different periods of pregnancy and what does it depend on, we will tell you in this material.

How is the baby growing?

At the very beginning of pregnancy, all babies, regardless of gender, race, heredity, grow exactly the same, adding millimeters and grams to their tiny weight weekly. All embryos grow at approximately the same speed, and only then, when the individual characteristics of the little person begin to appear, differences begin to appear.

It is possible to measure fetal growth even with the most modern ultrasound machine. only in the second half of the first trimester. Up to 8 weeks, only the diameter of the fetal egg is measured, and this criterion is considered the main one, indicating the growth of the embryo.

The dimensions of the baby itself are not yet available for measurements, the only exception being the coccygeal-parietal size, but it does not provide grounds for calculating the weight of the embryo.

You can talk about the weight of the fetus for the first time when undergoing an ultrasound examination, starting from the 11th week. It is at this time that the first differences between babies begin to appear - some babies are larger, others are smaller. At 7-8 weeks the baby weighs about 3 grams, but this is so small that the weight has no diagnostic value.

This table is compiled without taking into account the gender of the child. Some specialists who want to achieve the greatest accuracy in situations where the method of delivery and other important issues depend on the expected weight use tables developed by doctors from Germany to measure the weight of children of European appearance in the early 90s of the last century. It is compiled taking into account the gender of the fetus.

Table of normal values ​​for the expected weight of babies of different sexes:

It is no coincidence that the German tables, which are used all over the world, begin at 23 weeks of pregnancy. It is at this time that children of different sexes begin to develop bodies according to gender characteristics, which is why weight gain in boys and girls begins to differ from each other. At earlier stages, this difference between babies of different sexes is not present, or it is not expressed clearly enough and remains unnoticed for diagnosis.

Deviations from normal values

It is considered normal if a child is born at 39-40 weeks with a weight from 3000 to 3800 g. However, those babies who are born weighing up to 3 kilograms, and those who weigh more than 4.5 kg at birth, have neonatologists are not concerned.

Obstetricians urge expectant mothers not to panic about the difference in the numbers presented in the reference tables and their real numbers.

Firstly, you should always make an allowance for error (plus or minus 500 g at a minimum), and secondly, babies grow in leaps and bounds, so at 34 weeks the baby can upset the mother by lagging behind the average statistical norms, and by 36 weeks reach normal average value or even approach the upper limit of normal.

If the baby persistently exceeds the norm throughout all ultrasound examinations during pregnancy, they speak of a large fetus. The trend towards a larger baby can be noticed already in the second trimester. Such a conclusion cannot be made based on ultrasound alone. several studies are required over several weeks.

At the same time, attention is also paid to instrumental measurements - the circumference of the expectant mother’s abdomen and the height of the uterus. With a large fetus, the GMD usually exceeds the norm (at 32 weeks, when the norm is 32 cm, for example, this parameter is increased to 34 cm, and at 36 weeks, instead of the required 36 cm, it is about 39 centimeters).

If the baby in the mother’s womb noticeably lags behind the average values ​​and, over the course of several diagnostic measurements, “passes” only at the lowest limit of the norm (5th percentile), then doctors prescribe an additional examination, the purpose of which is to identify the consistency of the uteroplacental blood flow, possible pathologies of the fetus, including hereditary and chromosomal, intrauterine growth retardation, the presence or absence of intrauterine infections, Rh conflict.

To do this, they perform expert-class ultrasound, ultrasonography, do tests for infections, and perform clinical blood and urine tests. If necessary, the woman is sent for consultation with a geneticist and invasive diagnostics for the detection of chromosomal abnormalities.

Whether to agree to such measures is up to the expectant mother to decide, especially since modern medicine is ready to provide a harmless but expensive alternative to invasive diagnostic methods - a prenatal DNA test using blood from the mother’s vein.

A woman with suspected fetal malnutrition is prescribed regular monitoring of the baby’s condition using cardiotography (CTG), and additionally prescribed treatment (sometimes in a hospital), which includes taking vitamins and medications to improve uteroplacental blood flow. The estimated weight of the baby is monitored using intermediate ultrasound examinations.

Lagging behind the norms is not considered particularly dangerous if all the baby’s parameters are reduced symmetrically. Then this may be a variant of the norm, an anatomical feature of this child.

Starting from 7 months of pregnancy, the baby’s weight is not only a subject of burning curiosity for expectant mothers, but also important information for obstetricians. Based on general data about pregnancy and the approximate weight of the baby, they draw conclusions about the best way to bring the child into the world.

Reliability of determination and errors

As mentioned above, the most accurate method for determining the expected weight of the baby in the mother’s womb using ultrasound is considered. According to data received by American doctors from Florida, the error in the Hadlock calculation was approximately 14% of the baby’s body weight. In other words, the real mass differed from that predicted by the apparatus by 14% in one direction or another. This is the highest result to date.

The methods that obstetricians used before the widespread use of ultrasound, formulas and measurements are practically not used today, because there is no need for them. To obtain information about the possible body weight of the baby, you do not need to calculate anything. A computer program will help you calculate everything. The accuracy of the formulas (presented above and some others) is estimated at approximately 40-55%. Whereas with ultrasound, the accuracy of assessing a child’s body weight is almost 82%.

The most accurate method, as gynecologists like to say, is weighing. Therefore, those who want to find out how much the child weighs in grams just need to be patient and wait for the birth. They will answer this question with complete accuracy. All other methods resemble fortune telling. The size of the baby’s bones and head, even on an ultrasound, can indicate weight only indirectly, because there are children with long legs (like mom), but thin or with a big head (like dad).

Doctors themselves claim that the accuracy of determining fetal weight can be affected by the quality of visualization during ultrasound. If a woman is overweight, has extra pounds, or fat deposits on her stomach, then the error will increase. If a woman's pregnancy occurs against the background of oligohydramnios, the likelihood of a more significant error than 14% of body weight also increases. It is more difficult to calculate the weight of babies during pregnancy with twins, especially over long periods, because the limbs of one baby on an ultrasound can easily be mistaken for the limbs of another, as a result of which a significant error can creep into the predictions of the babies’ body weight.

If a child has developmental pathologies (hydrocephalus, microcephaly, gastroschisis), it is difficult to determine his expected weight, because the dimensions important for drawing up mathematical equations will not reflect the child’s real weight.

One of the main indicators that allows the doctor to draw conclusions about the normal or pathological course of pregnancy is the weight of the fetus. The baby grows and develops, changing significantly every week, so weight gain occurs quite rapidly. A shortage of grams, in comparison with the norm, may indicate all sorts of complications, in particular, oxygen or nutritional starvation of the fetus. Significant excess of normal weight can also signal various pathological processes. Therefore, it is very important to correctly calculate what the baby’s normal weight is for each week of pregnancy.

How to measure fetal weight

From the first days of pregnancy, the weight of the unborn child increases very quickly, but it can be accurately determined no earlier than the eighth week of pregnancy. Before this period, it is very small and does not even reach 1 gram.

Starting from the eighth week, weight can be calculated using ultrasound, measuring certain parameters. Today, the ultrasound method provides the most reliable information about the condition of the unborn baby, including its height and weight.

• child's thigh length
• biparental head size
• Head circumference
• chest diameter

With their help, taking into account the duration of pregnancy, the doctor can quite accurately determine the weight of the fetus using a special Hadlock method.

In later stages of pregnancy, the weight of the fetus can be calculated by an obstetrician-gynecologist during the next examination. To do this, he uses only two values: the height of the uterine fundus and the abdominal circumference. Having this data, as well as measuring the circumference of the wrist on the non-working hand, you can carry out the corresponding calculations yourself.

First, we get the initial data:

• The first number (let's call it A) is the product obtained by multiplying the height of the uterine fundus by the circumference of the abdomen.
• The second number (let's call it B) is the sum of the abdominal circumference and the height of the uterine fundus, divided by 4 and multiplied by 100.
• The third number (let's call it C) is obtained as follows: from the height of the uterine fundus, you need to subtract 11 (if the woman has thin bones) or 12 (if the bones are large), and then the result should be multiplied by 155. Measuring the circumference of the wrist will allow you to determine the thickness of the bone: a result of less than 16 indicates thin bones, and more indicates thick bones. The weight norm for large and small boned babies may also be slightly different.

In addition, it has certain errors in calculations, since it does not take into account the amount of amniotic fluid and other parameters. Therefore, preference is given to the ultrasound diagnostic method.

Normal weight for the fetus

While in the mother's womb, the baby grows very quickly and gains weight. The uterus also adapts to its parameters, which during pregnancy increases in size by almost 500 times, and in weight by 20.

At first, the baby’s weight changes very quickly. Every week he becomes almost twice as heavy.

This is due to the formation of more and more new organs, as well as their development. But starting from 14 - 15 weeks, this pace slows down a little, since the brain, which is responsible for the child’s activities, now begins to develop: he learns to blink, move his arms and legs, and move his fingers. The next burst of rapid weight gain occurs after 28 weeks.

And by the due date of 40 weeks, the baby reaches a weight of about 3.5 kilograms. Weight standards may differ for boys and girls, as well as for children born from overweight or thin parents.

Fetal weight by week can be presented in table form:

The norm given in the table is approximate, and if it does not correspond to the duration of pregnancy, then you should not get upset ahead of time. The final conclusion about how much a deviation from the norm affects the baby’s health can only be made after studying the entire picture of the course of pregnancy.

What determines the weight of the fetus?

As mentioned above, based on the baby’s weight week by week, the doctor can judge how well the pregnancy is going. The norm established for each term is not a panacea. But based on it, it is possible to timely identify and eliminate certain pathologies in the development of pregnancy.

Low or excessive fetal weight in itself cannot be the basis for making any diagnosis.

However, this is the basis for a more thorough examination. Usually, the presence of any pathologies in a child is determined during an ultrasound examination.

You should pay attention to the following factors that have a direct impact on fetal weight:

What does the weight of the fetus tell you?

In most cases, both doctors and future parents are more concerned about the baby's low weight. After all, if a full-term baby is born weighing less than 2 kg, this may indicate that he did not receive all the nutrients he needed in full, and also most likely experienced oxygen starvation in the womb.

All this can lead to problems in the child’s mental development. Therefore, it is important to promptly establish the reasons why the child is not gaining weight. Most of them can be eliminated during pregnancy and allow the baby to get stronger by the time of birth.

If the baby is born with low weight, then he must be examined.

However, in fact, bogatyrs who are born with a weight exceeding 4 kg cause no less trouble. Firstly, this causes difficulties for the mother herself during childbirth, since giving birth to a large baby naturally is quite difficult. Secondly, excess weight in a child may also indicate certain disorders.

Most often, the reasons for the appearance of large children are the same genetics and post-term pregnancy. And if it is unlikely that it will be possible to overcome the first factor, then post-maturity is usually dealt with by stimulating labor.

If we talk about pathologies that cause excess weight of the fetus compared to the norm, then these include:

• Diabetes. A pregnant woman with this diagnosis should be hospitalized at 32 weeks. Depending on her condition, complications during pregnancy, as well as the weight of the fetus, the issue of the expected date of birth is decided. In some cases, doctors resort to premature delivery of such women.
• Hemolytic disease of newborns. This disease occurs when the mother’s blood is incompatible with the baby’s blood group or Rh. Such a “conflict” is manifested by an increase in the level of bilirubin in the child, and in severe forms - swelling of the fetal body and an increase in its internal organs.
• Maternal obesity. There is no need to believe the statement that a pregnant woman should eat “for two.” With proper nutrition, the baby will receive all the nutrients he needs. If a woman allows herself extra calories during pregnancy, this cannot but affect her baby. This is especially true for those women who were overweight even before pregnancy. They are allowed to gain no more than 8 additional kilograms during pregnancy, which accounts for the weight of the fetus itself, the placenta, amniotic fluid and the uterus.

This calculator estimates the weight and height of a child according to his age, accurate to the day. Unlike, this calculator gives a comprehensive assessment of weight in strict accordance with the height and age of the child.

The ranges of values, methods and recommendations are based on methodological materials developed by the World Health Organization (WHO), which has conducted extensive research on the development of healthy children of different nationalities and geographical areas.

Please remember that our calculator generates results solely based on the data you provided. If you made measurements with a large error, the result will be inaccurate. This is especially true for measuring height (or body length).

If our calculator shows you the presence of any problem, then do not rush to panic: measure your height again, and have two different people take the measurements in turn and independently of each other.

Height or body length

In children under two years of age, it is customary to measure body length in a lying position, and from two years of age, height is measured, respectively, in a standing position. The difference between height and body length can be up to 1 cm, which may affect the results of the assessment. Therefore, if for a child under 2 years old you indicate height instead of body length (or vice versa), then the value will automatically be converted to that required for correct calculation.

What is the height (body length)

Growth is the most important indicator that should be monitored monthly (see). Receiving ratings of “short” and “very short” may be a consequence of prematurity, illness, or developmental delay.

Large height is rarely a problem, but a rating of "extremely tall" may indicate the presence of an endocrine disorder: this suspicion should also arise if a very tall child has both parents of normal average height.

Extremely short Significant growth retardation. It can also lead to excess weight. The participation of a specialist is necessary to identify and eliminate the cause of the lag. short Growth retardation. It can also lead to excess weight. Specialist consultation is required. Below the average A short child, height within normal limits. Average This is the height of most healthy children. Above average Tall child, height within normal limits. High Such large growth is not common, but it does not indicate the presence of any problems, so it is considered normal. Usually this growth is hereditary. Very high (excessively high?) Excessive height in a child is usually hereditary and is not a problem in itself. However, in some cases, such growth may be a sign of an endocrine disease. Therefore, rule out the possibility of an endocrine disorder by consulting a specialist. Height does not correspond to age You probably made a mistake when indicating the child's height or age.
If the baby’s growth is really the same as you indicated, then there is a significant deviation from the norm, which deserves special attention from an experienced specialist.

How does weight correspond to height?

The ratio of height and weight gives the most meaningful idea of ​​the harmonious development of a child; it is expressed as a number and is called the Body Mass Index, or BMI for short. This value is used to objectively determine weight-related problems, if any. And if there are none, then they make sure that the BMI is normal.

Please note that normal body mass index values ​​for children are radically different from those for adults and very much depend on the age of the child (see). Naturally, our calculator estimates BMI in strict accordance with the child’s age.

Extreme wasting, severe underweight Severe body weight deficiency. Severe exhaustion. Nutritional correction and treatment as prescribed by a doctor are necessary. Wasting, underweight Body weight deficiency. Insufficient weight for specified height. It is recommended to adjust your diet as prescribed by your doctor. Reduced weight Weight is within normal limits. The child is less well-fed than most of his peers. Norm Ideal weight to height ratio. Increased weight (risk of being overweight) The child's weight is normal, but there is a risk of gaining excess weight.
In this case, it is recommended to pay attention to the weight of the child’s parents, because Having obese parents significantly increases the risk of a child gaining excess weight.
In particular, if one of the parents is obese, then with a 40% chance the child will gain excess weight. If both parents are obese, the likelihood of the child becoming overweight increases to 70%. Overweight It is recommended to adjust your diet as prescribed by your doctor. Obesity Nutritional correction and treatment as prescribed by a doctor are necessary. Obesity: Nutritional correction is necessary as prescribed by a doctor. Not assessable You may have made a mistake when specifying the child's height, weight or age.
If all the data is correct, then there is a significant deviation from the norm, which requires special attention from an experienced doctor.

What is the weight

A simple weight estimate (based on age) usually gives only a superficial idea of ​​a child's developmental pattern. However, receiving ratings of “Low weight” or “Extremely low weight” is a good reason to consult a specialist (see). The full list of possible weight ratings is below:

Severely underweight, extremely low weight Underweight, low weight The child is likely malnourished or has developmental delays. It is necessary to consult a specialist. Less than average Weight is below average, but within the normal range for the specified age. Average This weight is typical for most healthy children. Above average In this case, compliance with the norm should be assessed by body mass index (BMI). Very big In this case, weight is assessed using body mass index (BMI). Weight is not appropriate for age You probably made a mistake when indicating the child's weight or age.
If all the data is correct, then the baby may have problems with development, weight or height. See height and BMI estimates for details. And be sure to consult an experienced specialist.

During 9 months of pregnancy, a charming, rosy-cheeked baby grows from a pair of cells invisible to the eye.

And this is a real miracle! During this period, a strong skeleton and organ systems have time to form, and the endocrine glands begin to function. Some organs manage to go through several stages of development.

It is important for an expectant mother to know how her baby grows and develops at each stage of pregnancy. This is especially of concern to women in the first half of their term, when it cannot yet be reliably felt. Knowledge about the stages of embryo development helps the mother imagine the baby and strengthens the emotional connection between her and the child.

Modern medical equipment allows you to obtain accurate information about the stage of fetal development and control its weight and size. These data are an important indicator of the normal course of pregnancy. Using them, you can diagnose pathology at the very beginning of its development and take timely measures.

In obstetric practice, it is customary to divide the pregnancy period into 3 trimesters.

Each period is characterized by its own hormonal changes in the woman’s body, the indicators of clinical tests for each stage of pregnancy are known, and the possible risks of each period are taken into account.

What happens to the baby himself at this time?

First trimester

The first 8 weeks of pregnancy are sometimes called the embryonic stage of development. Over the course of two months, only repeated cell division occurs, their differentiation depending on future functions, but for most of this period the embryo still does not at all resemble the future little person. And only by the end of the 8th week will it be possible to distinguish between a large head and a small body (<3 см) с зачатками конечностей.

At the end of the second month, the embryo weighs only about 2 g, but just a month later, by the end of the first trimester, it already weighs 10 g.

The fetus is still small, but in just a month the weight increases 5 times. The last month of the first trimester opens the fetal stage of fetal development, which will last until the end of pregnancy.

Second trimester

During the second trimester, the skeletal and muscular systems are formed. The fetus actively grows in length, the proportions of the head and body change, and the limbs develop. Muscle tissue grows and at about 18-20 weeks the movements of the unborn baby are so active that even women with their first pregnancy feel movements.

However, the main increase in muscle mass will occur only in the third trimester.

The weight of the fetus at the turn of the second and third trimester is approximately 500-600 grams.

Thus, in 3 months the weight increased more than 50 times. Average weight gain is 60-70 grams per week.

A weight of 500 grams is an important developmental milestone: in the case of even such a low birth weight, the baby will not be classified as a late miscarriage, but may be sent to the premature ward. There is experience in successfully nursing such babies.

Third trimester

In the last months, when all organs are formed and begin to function, the fetus grows rapidly, gaining muscle mass. The average weight gain in the third trimester is about 200 g per week.

But after 36 weeks, weight gain noticeably slows down. This is related to.

By the time of birth, the average weight of the baby will be 3.5 kg.

Those. it grows 6 times in the last trimester. The weight gain during this period is the largest, about 2500 g.

Table. Fetal weight by week - normal

Determination of fetal weight by ultrasound

Allows you to most accurately calculate its mass based on the data obtained.

This takes into account parameters such as gestational age, fetal head and chest circumference, and hip size.

Some errors are possible due to the awkward position of the baby in the uterus or during multiple pregnancies. But in general, this method is the most informative.

Calculation of fetal weight using formulas

If you do not have the opportunity to go for an ultrasound, or do not want to disturb the baby’s peace for religious or other reasons, the approximate weight of the fetus can be calculated independently at home. For this you will need a measuring tape. Formulas can be used starting from 32 weeks of pregnancy.

Jordania formula

Basic data for calculation: abdominal circumference (AC) and uterine fundus height (UF).

Fetal weight (g) = coolant (cm) × ID (cm)

This formula is called the Jordania formula.

In addition, for higher accuracy of the result, various coefficients entered by obstetricians are used.

Johnson calculation

This method, in addition to the size of the abdomen and the height of the uterus, uses a correction factor depending on the weight of the pregnant woman. If a woman weighs less than 90 kg, the Solovyov coefficient will be equal to 11, if a woman weighs more than 90 kg, the coefficient. equals 12.

Solovyov's method

The Solovyov coefficient also takes values ​​of 11 or 12, but is determined by the size of the wrist. If a woman’s wrist circumference is more than 16 cm, coefficient = 12; if less, subtract 11 from the height of the uterus.

Fetal weight = (VDM - coefficient) × 155.

Yakubova's method

The Yakubova formula is an improved version of the Zhordania formula

Fetal weight =((FB - uterine height) / 4) × 100

Lankowitz formula

This is a more complex calculation proposed in 1961 by obstetrician A.V. Lankowitz. It takes into account additional parameters: the height and weight of the pregnant woman.

Fetal weight = (FH + VD + height + weight) × 10

For this formula, height, abdominal size and uterine height are measured in cm, mother's weight in kg. The resulting weight of the fetus will be in grams. The Lankowitz formula has proven to be accurate in about 55% of cases, and in 35% it gave a small error of 200-500 g.

Bublichenko method

The calculation “according to Bublichenko” is as simple as possible:

Baby's weight = mother's weight / 20.

Dobrovolsky's technique

Dobrovolsky's method, like Bublichenko's method, is based on the average ratio of the weight of mother and child. But in Dobrovolsky’s formula, a special coefficient (0.5) is used for this, showing the ratio of the body weight of the mother and the fetus at 39-40 weeks of pregnancy.

There is probably not a single expectant mother in the world who, while pregnant, did not want to know how much her child would weigh. Of course, pregnancy is a rather difficult time from a physiological point of view, but from a psychological point of view, it is a very pleasant and joyful state. The article will discuss how to calculate the weight of the fetus.

Stroikova's formula

Let's start with the fact that there are different formulas for calculating the weight of the fetus. These formulas were developed by different scientists.

So, according to Stroikova’s method, the formula for calculating the weight of the fetus will be as follows:

X = (MB: K + coolant * VDM) / 2

In the formula, X means the estimated weight of the fetus, MB is an abbreviation for the body weight of the pregnant woman, WC is the abdominal circumference, IMR is an abbreviation for the height of the uterine fundus above the womb, and K is a constant.

The X value is measured in grams, MB is measured in kilograms, and coolant and air flow are measured in centimeters. The K value depends on the mother's body weight. If the mother weighs up to 51 kg, then K is equal to 15; if body weight is 51-53 kg, then K is 16; if MB is in the range of 54 - 56 kg, then K = 17; if the mother’s body weight is from 57 to 62 kg, then K is 18; if the pregnant woman’s weight is between 63-65 kg, then K will be equal to 19; if MB = 66-73 kg, then K = 20; if MB = 74-81 kg, then K = 21 and if MB is more than 82 kg, then K will be equal to 22. If you calculate the weight of the fetus using this formula, then there is an error within two hundred grams.

Yakubova's formula

Now about how to determine the weight of the fetus using Yakubova’s formula. Here, the height of the uterine fundus is added to the abdominal circumference, then the indicator is divided by four and multiplied by 100.

Rudakov's formula

Rudakov proposes this approach to determining the weight of the fetus: you need to measure the semicircle of the width and length of the palpated fetus, and then multiply them. As a result, the resulting indicator is substituted into a table developed by the scientist, and the weight of the fetus is determined. It should be said that the table has three columns where this index can be substituted. These columns represent values ​​for large, preterm, and term deliveries.

In addition, there are norms for the weight of the fetus. But it should be said that each fruit has its own norm and grows according to, so to speak, its own rules. Typically, many different tables offer indicators that reflect some kind of average.