Determination of the expected height and weight of the fetus. Deviations from normal values. Normal fetal weight

Fetal weight by week of pregnancy is a very important diagnostic indicator, which is assessed using ultrasound. Lack or excess weight indicates the development of a pathological process.

Normal intrauterine development is determined by many indicators. One of these parameters is the mass of the child. Fetal weight by week of pregnancy with deviations up or down indicates insufficient nutrition or the formation of hypoxia.

What determines the weight of the fetus during pregnancy?

The weight of the child depends on the functioning of the placenta and the incoming nutrients with oxygen. Starting from the second trimester, the fetus increases to 80 grams. In the later stages, the seven-day gain reaches 200 grams, but before labor the pace slows down significantly due to the death of the placenta.

The indicator also depends on the following factors:

• unbalanced maternal diet;
• stressful situations during pregnancy;
• chronic diseases;
• toxicosis;
• smoking and alcohol abuse;
• genetic predisposition.

The weight of the baby during intrauterine development also depends on gender. Boys are born larger than girls.

Normal fetal weight by week of pregnancy

In the first seven days after conception, the fertilized egg begins to divide, forming the placenta and fetus. Until the 7th week, all vital organs are laid and formed. The outlines of a person appear - legs, arms, head, heart muscle. Already at the 5th week you can measure the baby.

In the second trimester, the baby begins to grow rapidly. The rate of increase is about 80 g/week. Further, the weight of the fetus grows even more rapidly, reaching up to 300 g/week. During the 9-month period of intrauterine development, the uterus increases 500 times.

Doctors, when assessing parameters on ultrasound, are guided by general indicators of size and circumference. The main component is the positive dynamics of the intrauterine formation of the baby and its full development.

The approximate weight of a baby at 30 weeks is up to 1.4 kg. Any minor deviation can be perceived as a pathology or a normal condition, depending on the individual parameters of the expectant mother and the baby itself. By the beginning of labor, the baby reaches at least 3 kg 100 g.

Table of fetal weight norms by week of pregnancy

The estimated fetal weight in the early stages is calculated using ultrasound. At a later stage, the doctor, thanks to measurements of the abdominal circumference and the height of the uterus, can calculate this indicator.

Calculated child weight norms by week of pregnancy are presented in the table:

weeks	Lengthcm	Weight, g
11 week	4,1	7
12 week	5,4	14
Week 13	7,4	23
Week 14	8,7	43
Week 15	10,1	70
Week 16	11,5	100
Week 17	13	140
Week 18	14,2	190
Week 19	15,3	240
Week 20	25,8	300
21 weeks	26,7	360
Week 22	27,8	430
Week 23	28,9	500
Week 24	30	600
Week 25	34,6	670
Week 26	35,6	760
Week 27	36,6	875
Week 28	37,6	1000
Week 29	38,6	1150
Week 30	39,9	1320
31 weeks	41,1	1500
Week 32	42,4	1700
Week 33	43,8	1900
34 week	45	2150
Week 35	46,2	2380
Week 36	47,4	2500
Week 37	48,6	2800
Week 38	49,8	3000
Week 39	50,7	3300
Week 40	51,2	3400

Calculate baby's weight during pregnancy by week - calculator

The most informative method for making calculations during pregnancy is ultrasound. The specialist measures the length of the thigh, the size and circumference of the head, and the diameter of the chest. After which, he receives a ratio, which is checked against the table of norms.

During the examination, the doctor is able to calculate the baby’s body weight using a special formula that takes into account the height of the uterine fundus, abdominal circumference and bone thickness of the woman. The method is used in the third trimester. In case of significant deviations, a certain diet and drug therapy are prescribed.

For the full development of the baby, both excess and decreased levels are equally dangerous. It is worth adhering to reasonable dietary standards and not neglecting walks in the fresh air, and a calculator for the weight and height of a child during pregnancy will help you calculate acceptable limits.

With each week of pregnancy, the embryo grows and develops, turning into a full-fledged baby by the end of the 9th month. Its weight and size are among the important indicators that are monitored by doctors throughout the entire gestation period. Deviations of these parameters from the norm indicate the development of defects and anomalies, so it is important to identify them in time (before the 20th week) in order to prevent an unfavorable course of pregnancy.

How does a baby's weight change during pregnancy?

The weight of the fetus changes every day, and after 30-32 weeks the increase becomes more noticeable. What does this depend on? The process occurs at a rapid pace due to the ability of the uterus to stretch significantly.

In its normal state, the size of the female reproductive organ reaches 6-8 cm, weight - about 60 grams. By 32-34 weeks of gestation, the uterus increases to almost 30 cm, and by 38-40 weeks it reaches 40 cm and weighs more than a kilogram. This unique ability of the organ is inherent in nature itself, due to which suitable conditions are created for the full formation and growth of the baby inside the womb.

Many pregnant women are concerned about the question of how much weight the baby gains by week and what to do if weight gain is bad? Sometimes, in order to increase the baby’s weight at 34-36 weeks, specialists prescribe special mixtures to the woman. They help the baby gain the necessary indicators before birth.

In the first trimester

Doctors determine fetal growth and weight using ultrasound. The embryo is visible on the device monitor only from the 8th week of gestation. Until this time, it is tiny in size.

Starting from the 8th week of pregnancy, the embryo becomes human-like. It has a large head, a small body with the rudiments of arms and legs. By week 4, the weight of the embryo is approximately 1.5-2 g. After 30 days, the weight increases 5 times, although the embryo still remains tiny.

In the second trimester

From the 20th week, the baby’s organs are actively forming, and muscle tissue is also appearing. He grows in length, the proportions of his body change. The limbs take on the correct shape. In the period from 18 to 20 weeks, the expectant mother begins to feel the first movements of the child.

In the second trimester, the baby’s weight increases approximately 50 times and at 24 weeks reaches 0.5-0.6 kg (see also:). It follows from this that the fetus gains about 60 grams per week.

In the third trimester

The third trimester (starting from week 30) is characterized by increased muscle mass gain, since all vital organs have already been formed (see also:). The baby gains on average 200 g per week. In general, starting from 7 months, its weight increases 6 times during the entire third trimester. During this period, the fetus rapidly gains weight and by the end of the 37th week already weighs 2.5-3 kg.

Child weight norms by week: table

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Routine examinations of a woman allow doctors to determine weight indicators in order to determine whether the baby is developing correctly and whether its weight corresponds to norms. If deviations from the norm are greater or lesser, specialists may prescribe special therapy.

The average fetal weight by week of pregnancy can be seen in the table:

A week	8	9	10	11	12	13	14	15	16
Weight, g	1	2	4	7	9	14	21	30	40
A week	17	18	19	20	21	22	23	24	25
Weight, g	50	140	200	220	280	400	460	550	650
A week	26	27	28	29	30	31	32	33	34
Weight, g	750	800	950	1000	1100	1300	1600	1900	2100
A week	35	36	37	38	39	40
Weight, g	2300	2500	2800	3100	3200	3200

Babies born at 37 weeks of pregnancy or later are considered full-term. Normal weight ranges from 2.5 to 4.5 kg. As a rule, boys are born slightly larger than girls.

Deviations in a child’s birth weight are not only due to gender. This indicator is also affected by:

• heredity;
• chronic diseases of women;
• fetal malformations;
• placental insufficiency;
• lifestyle of the expectant mother.

How is weight determined using ultrasound?

The doctor determines the weight of the fetus using the results of an ultrasound examination. In this case, the following are considered important indicators:

• week of pregnancy;
• length of the child’s body and limbs;
• circumference and size of the head (the biparietal indicator is determined by measuring the segment between the two widest areas of the skull);
• abdominal circumference;
• hip size.

Sometimes calculations are not so accurate due to the unfortunate location of the fetus in the uterine cavity. The reliability of the indicators is also influenced by the amount of amniotic fluid and the number of fetuses in the uterus (multiple pregnancy).

Formulas for calculating fetal weight

The method of calculating a child’s weight based on ultrasound results is considered the most accurate. Sometimes they resort to mathematical formulas to calculate the approximate weight of the fetus. This procedure can be carried out at home, starting from the 32nd week of gestation. During this period, the average weight of the fetus reaches 1500 g. A woman needs to arm herself with a measuring tape and a calculator. The most popular calculation methods are presented in the table:

Calculation method	Preliminary data	Formula	Notes
Jordania formula	Pregnant woman's abdominal circumference (AB), uterine fundus height (UF), all parameters are measured in centimeters	Weight (g) = Coolant x HP	For a more accurate calculation, the doctor uses special coefficients
Yakubova's method	The parameters are the same	Weight = (coolant + VDM) x 100/4	An improved version of the Jordania formula
Johnson calculation	In addition to the above parameters, the Solovyov coefficient is used, which is calculated based on the woman’s weight. If body weight is less than 90 kg, the coefficient will be 11, if more than 90 kg, then 12.	Fetal weight = (VD-coefficient) x 155
Solovyov's method	It is necessary to measure the height of the uterine fundus and wrist circumference. If the last parameter is less than 16 cm, the coefficient will be 12; if the wrist is more than 16 cm in circumference, the Solovyov coefficient will be 11.	The formula is the same
Dobrovolsky's technique	Mother's height, 0.5 coefficient applied	Fetal weight = (woman’s height – 96)x0.5
Lankowitz formula	It is considered one of the most difficult methods. A woman’s height, weight, abdominal circumference, fundus height	Fetal weight = (FH + VD + height + weight) x 10	In half the cases, Lankowitz's formula gives accurate results. In other cases, calculation errors are possible (approximately 200-500 g)
Bublichenko method	The simplest and most uncomplicated method, where you only need one parameter - the mother’s weight	Baby's weight = Mother's weight / 20

Deviations from the norm and their causes

The weight of the unborn baby is influenced by many factors, for example, the poor health of the mother or her illness during pregnancy. The most common causes of low birth weight of a newborn:

1. If one of the parents has a frail build and short stature, the child may be born with low weight.
2. When a woman is diagnosed with anemia. This condition negatively affects the formation of the placenta, which affects the provision of nutrients and oxygen to the fetus. As a result, the baby is born very small and may lag behind in development.
3. Inappropriate lifestyle of the expectant mother. If a woman does not pay due attention to her diet, drinks alcohol or smokes, all this affects the growth and development of her child.

The weight of a newborn in 10% of cases is above normal and can reach 5 kg. The reasons for such deviations are:

1. Maternal diabetes mellitus. The disease affects the intrauterine development of the child. The fetus receives a large amount of insulin, due to which its weight increases significantly. Prenatal obesity may even develop. Women with this diagnosis must adhere to a special diet and follow all the recommendations of specialists, then the baby will be born healthy.
2. Poor nutrition during pregnancy. If a woman eats a lot of carbohydrates (baked goods, sweets), this affects not only her weight, but also the weight of the baby.
3. Severe toxicosis in the first and third trimesters. This condition is accompanied by edema, which does not have the best effect on the condition of the fetus.
4. Hemolytic disease of a child. This pathology appears even before birth due to Rh conflict. If a woman is Rh negative and her husband is positive, the child will inherit Rh from the father. The condition is characterized by the formation of edema in the body cavity. Due to this accumulation of fluid, the mass increases.

According to statistics, a large baby is born in those families where there are already one or two children. This is explained by the fact that a woman is already more aware and in control of her condition during her second or third pregnancy. The expectant mother worries less and does not make the same mistakes associated with her lifestyle, so the fetus grows better and gains weight.

Deviations from the norm in a larger direction in the weight of the child at birth do not have the best effect on the birth process. A large fetus can cause many problems during childbirth:

• discrepancy between the size of the child’s head and the woman’s pelvis;
• ruptures are possible when the fetus passes through the birth canal;
• the likelihood of postpartum hemorrhage (possible due to insufficient contractile function of the uterus after delivery).

To avoid such unpleasant consequences, doctors prescribe a caesarean section. It can be planned or emergency.

The question of what the weight of the fetus should be is of interest to every woman. According to statistics, 40% of mothers expecting a baby consider methods for determining the expected weight of the fetus to satisfy personal interest. The remaining 60% want to know the exact value in order to formulate a plan to facilitate the birth process.

It is worth noting that obstetric practice has recently included calculations and various formulas for determining the estimated weight of the fetus.

Basic methods for determining fetal weight

To determine a child's weight, you should know several important parameters. It is necessary to determine the woman’s body weight, and then perform an ultrasound. The information obtained is used to calculate the approximate weight of the fetus.

There are a large number of techniques for determining the estimated weight of the fetus, thanks to which you can easily find out the weight of the child. These are the formulas:

1. Lankowitz.
2. Bublichenko.
3. Yakubova.
4. Jordania.

To carry out calculations you need to know:

• woman's body weight;
• height (in cm);
• abdominal diameter;
• VDM (height of the uterine fundus).

Of course, the list is not limited to this, but nowadays medical equipment has been improved to such an extent that it itself calculates and takes into account even minor details in the calculations.

Determination of fetal weight - algorithm using the Lankowitz formula

It is not for nothing that the Lankowitz formula comes first in the estimated weight of the fetus, since it helps to give the result closest to the real value. A small error, of course, is always and everywhere.

1. Add up the uterine fundus (uterine fundus height) and OB (abdominal circumference).
2. Add the resulting value to the height of the expectant mother (in cm) and her body weight (in kg).
3. Now we multiply the final digital indicator by ten.

In this way, the estimated weight of the fetus is determined - Lankowitz manipulation.

Calculation algorithm using Bublichenko’s formula

1. The weight of the expectant mother should be divided by 200.
2. Multiply the result by 10. This is approximately 0.7% of the total weight of a pregnant woman.

Currently, the formula is practically not used.

Determination of the estimated fetal weight using the Yakubova formula

Algorithm:

• Find the sum of VDM and coolant.
• We divide the result of the first action by four.
• Find the product of the resulting number and 100.

This method also cannot be considered frequently used in clinical practice.

Determination of the estimated fetal weight according to Zhordania

The calculation is performed in just one step - find the product of coolant and air flow (in centimeters). The result obtained will be the expected weight of the baby (in grams).

Based on the above, we can conclude: determining the estimated weight of the fetus is not such a difficult manipulation (provided that all the values ​​used are known).

Online calculators are popular on the Internet, with the help of which you can easily calculate the approximate weight of a newborn. To use these methods, you should know how to correctly calculate all these parameters.

How to find coolant?

For this you need a measuring tape (in cm). The meaning is as follows: at the level of the navel, we wrap around the stomach. We measure at the received mark. We use it for calculations.

How to find VDM?

The height of the uterine fundus can be easily determined using the same measuring tape. The beginning of the tape should be applied to the upper protruding part of the abdomen (to the curve in the stomach or near the navel), and the end of the tape should be applied to the upper part of the pubis. The result obtained (in centimeters) will be the height of the uterine fundus. After 16 weeks, the UMR corresponds exactly to the gestational age.

Some nuances that can slightly allow for an error in determining the weight of the fetus:

• multiple pregnancy;
• polyhydramnios;
• the expectant mother is overweight.

Is there a norm for fetal weight, what should it be? The norm has its own specific exact limits: 2.5-4 kg during full-term pregnancy (after 37 weeks). For other periods, their own standards have been developed.

With weight loss, they speak of intrauterine fetal weight loss. The placenta does not function correctly and the baby does not receive full nutrients and oxygen. Hypoxia develops - oxygen starvation of the fetus, and weight loss is noted. It is possible to give birth to a child weighing up to 2.5 kg.

If a newborn is born weighing more than 4 kg, it is considered large. After birth, you need to undergo regular examinations and medical examinations. Such children have a fairly high risk of developing diabetes and obesity. It is for these reasons that the expectant mother is obliged to monitor not only her general health, but also her weight, abdominal volume, etc. If something seems strange, it is best to immediately consult a doctor.

Fetal weight and delivery

How can you interpret the weight of the fetus in order to find the most suitable birth option?

• If the baby's weight is 4 kg or more, then the obstetrician-gynecologist performs a planned operation, during which the fetus is removed from the uterus (an incision is made on it). The operation is called a caesarean section. But in medical practice there are also cases where large babies were born naturally, and everything went well. The issue is resolved individually based on the size of the mother’s pelvis, the condition of the fetus and other related factors.
• Low body weight is defined as a person weighing 2.5 kg or less. We are usually talking about premature babies, that is, those born before their due date. This affects the development of such babies. Due to the high risk of complications during natural childbirth, doctors often suggest a cesarean section. You can give birth naturally, but it’s worth talking with an obstetrician-gynecologist, as all the nuances and errors in all measured data should be taken into account.

Now we can draw a general conclusion. Fetal weight matters when choosing a birth method. There are a large number of different calculations with which you can determine the weight of the fetus that is close to the true value, but still the final result can be obtained only after a comprehensive summing up and analysis of all the nuances.

Calculation of fetal weight by ultrasound

Correctly determining the child’s body weight is very important not only for the expectant mother, but also for the gynecologist. Doctors use special tables and standards for this. In order to calculate the weight of the fetus using ultrasound, you can use an online calculator. You just need to substitute the characteristics, and the program will independently calculate the weight of the baby.

During the first sound examination of the fetus (at 12-14 weeks of pregnancy), it is very difficult to determine its weight. At this time, an ultrasound is performed to assess the condition of the fetus and identify severe malformations. The problem is that this information is not enough to calculate the weight of the fetus using ultrasound. Using this method, in the first trimester of pregnancy you can only determine the embryological gestational age and the size of the baby. The doctor, comparing it with the obstetric period, is able to determine whether there is a lag in the child’s weight. The obstetric period of pregnancy is the 1st day of the last menstruation. Of course, in this case it is impossible to exclude inaccuracy in weight calculations.

In order to use the online calculator, you should have more extensive ultrasound data than at week 12. To do this you need to know the following parameters:

• embryological period of pregnancy in weeks;
• characteristics of the fronto-occipital region FOD;
• head diameter HC;
• biparietal diameter BPD;
• abdominal circumference AC;
• femur length FL.

The second screening ultrasound is performed at 20 weeks of pregnancy. This study provides insight into the size of the fetal tibia, humerus, and forearm bones. Such information will help determine the weight of the fetus. Here is the algorithm for determining the estimated fetal weight using ultrasound. In clinical practice, doctors rely on tables developed for each period. Fetal weight assessment is carried out starting from the second screening at 18-21 weeks, then during the third screening (32-34 weeks) and then according to indications until birth.

In conclusion, it should be emphasized that the weight of children plays a significant role in establishing the obstetric strategy for the management of childbirth. It is possible to determine the approximate weight of the fetus using different methods, but the final decision on the weight of the fetus is formed on the basis of a single consideration of the results obtained, since they depend on many conditions. You can accurately estimate body weight after birth by weighing the newborn baby. In a similar way, you can establish the accuracy of your own calculations.

During routine visits to the gynecologist during pregnancy, a woman must be weighed and her abdominal girth measured to know how the baby is growing and developing. One of the main characteristics that the doctor records is the weight of the fetus by week of pregnancy, its size and the length of the skull circumference. All these indicators are important in order to assess the baby’s health, its development, and to notice the onset of the disease in time if it suddenly happens. It is especially important to calculate the weight of the fetus by week of pregnancy in the later stages, before childbirth, since the time and method of its birth often depends on the size of the child.

Equally important is regular examinations of mother and child in the first months of a woman’s pregnancy. During this period, all systems and organs in the baby’s body are formed, the placenta and umbilical cord are being formed, and therefore doctors carefully monitor the condition of the embryo. In the first months of pregnancy, the weight of the fetus is very small, and therefore doctors measure only the weight of the mother, and the child is examined and measured using ultrasound.

The values ​​given in the tables below are approximate averages. The weight and size of the embryo by week and month depends on the constitution of the mother and father of the child, on hereditary factors, the rhythm of life and the mother’s diet during pregnancy, and hereditary diseases. Only a doctor can say for sure that the child is developing normally or not normally, after studying the data from several examinations, ultrasounds and tests of the mother, her medical history and medical record.

In later stages, the weight and other indicators of the embryo may differ from normal to a greater or lesser extent. The intrauterine development of a child depends entirely on the mother’s lifestyle, and if the mother does not eat well, abuses sweets or fast food, then the baby can also gain weight faster than necessary. With a multiple pregnancy, the weight of each baby is usually less than with a standard singleton pregnancy.

Fetal weight and size by week of pregnancy in the first trimester

The first screening - a complete examination of the woman and baby - is usually carried out at 10-13 weeks of pregnancy. Usually during this period, women are convinced that they are pregnant and register at the antenatal clinic, where the study is carried out and the course of pregnancy is monitored. The weight of the fetus during this period of time ranges from 4 grams at week 10 to 25 grams at week 13, and most of the space in the uterus is occupied by amniotic fluid. The doctor receives basic information from a blood test and measuring the size of the embryo using ultrasound.

The size of the embryo by week in the first trimester should be as follows:

If the weight or size of the embryo differs slightly from the average, do not be alarmed. Most often this is due to an incorrect determination of the gestational age, and since the baby gains several grams every day, small discrepancies are acceptable.

The gestational age can be calculated in obstetric weeks, that is, counted from the date of the last menstruation, or measured from the date of conception. In the first case, it is believed that pregnancy occurred 2-3 weeks earlier, in the second the error will be only a few days. Due to inaccurate calculation of the gestational age, normal indicators may shift in one direction or the other.

At the first screening, the doctor evaluates not only the weight and size of the fetus by week of pregnancy, but also measures the length of some of the baby’s bones. Be sure to take into account:

• The size and length of the femur shows how correctly the skeleton is developing. At 12 weeks, the embryo has a fully formed skeleton and all the bones are formed, which will only continue to increase in size. Using an ultrasound, the doctor looks at how correctly the skeleton is developed, how the length of the femur correlates with the size of the spine, shoulder, tibia and radius bones;
• The size of the chest also shows the presence of pathologies in the development of the baby and the correct formation of internal organs. The chest circumference should be proportional to the growth of the embryo. Some studies do not calculate the circumference of the chest, but its diameter;
• Biparental head size (BSH), that is, the width of the skull in a straight line from temple to temple, is one of the most important indicators of normal development. The size of the head shows how well the child’s brain and the bones of his skull are developing, and going beyond the normal range may indicate Down syndrome and several similar diseases, anencephaly, hydrocephalus and other pathologies that serve as a reason for termination of pregnancy. In the later stages, the BPR is replaced by the fronto-occipital size;
• The growth of the embryo is calculated by the size of the spine, from the crown of the embryo to the tailbone, and the length of the legs is not taken into account. The size of the fetus changes over the weeks of pregnancy, but the baby always develops strictly in proportion. Therefore, if all parameters except one are normal, then we can talk about pathology in the child’s development.

• In addition to the growth of the embryo, doctors in the first trimester measure and compare the size of the fertilized egg and the child’s heart rate with the norm. Using these indicators, you can much more accurately determine the age of the embryo and its state of health.

Fetal size by week of pregnancy in the second trimester

In the second trimester, during the second screening, the baby in the mother's womb has grown enough to be able to see its face, fingers and toes, and all internal organs. The second screening is aimed at how much the child has grown, his weight and height, the structure of the face and head, the maturity of the lungs and the structure of all internal organs.

Fetal weight and size by week of pregnancy in the second trimester:

Other parameters, such as the girth of the skull and chest, the length of the bones of the legs and arms, are also recorded during screening and ultrasound diagnostics, but they are not as important as in the first trimester. Typically, the second full examination is carried out at 17-18 weeks of pregnancy, when the weight of the fetus in the womb has increased so much that the child can be fully examined. Typically, a second study is prescribed if it is necessary to confirm or refute information obtained in the first trimester, to track the dynamics of pregnancy, and to verify the presence or absence of pathologies.

The second screening is considered optional if the woman is healthy and leads a healthy lifestyle, she is under 35 years old, all her children were born healthy and the pregnancy is developing normally. But you can undergo this study at your own request in a public or private clinic.

Third trimester: fetal weight by week

During pregnancy, the weight of the fetus changes over the weeks and months, and by the third trimester, the baby in the mother's womb turns from an embryo into a baby ready to be born. The third screening, unlike the second, is important for the normal management of pregnancy and preparation for childbirth, and based on its result, the doctor can either prescribe a cesarean section for the mother or allow a natural birth, and in case of a poor prognosis, the woman can be admitted to the hospital “for preservation” .

During the ultrasound diagnostic process during the third screening, doctors look at the size of the embryo by week and day from the crown to the sacrum, the weight of the child, the degree of development and girth of the skull.

Fetal weight by week of pregnancy in the third trimester:

During the third screening, doctors diagnose a number of diseases and malformations that the child may suffer from, assess the condition of the umbilical cord, uterus, size and condition of the placenta. The normal screening period is around 30-34 weeks, when the baby is actively gaining centimeters of height and grams of weight. Often, along with ultrasound diagnostics, Doppler measurements are performed to assess the movement of blood through the vessels and CTG to listen to the rhythm of the child’s heart. Sometimes the dates of the study are shifted to a later date.

Needless to say, pregnancy is a very important and exciting event in the life of every woman. The anxious anticipation of the birth of a baby is sometimes replaced by anxiety and worry about whether it is developing correctly in the womb. For any expectant mother, the main question remains: is everything okay with her child?

Not out of curiosity

It is very important throughout pregnancy to monitor the main parameters of the baby’s development and know how to calculate the weight and height of the fetus, what their timing is. This is necessary in order to have a complete picture of the health of the unborn baby.

Until the eighth week, the fetus is very small, its weight barely reaches one gram. Therefore, it is impossible to monitor the weight of the unborn child before this period, and it does not make sense. Then its weight increases very quickly, almost doubling, as the formation of the main organs occurs.

By the 15th week, the fetal brain is formed and the development of certain motor functions begins. Weight gain during this period is slower. And already from 28-32 weeks the baby begins to actively gain weight. There is a comprehensive growth of the child’s organs and systems, the formation of his reflexes and sensitivity.

Today, every pregnant woman has the opportunity to calculate the weight of the fetus by week. In addition to the usual arithmetic calculations of the baby’s weight and height, automatic calculation methods also come to the rescue.

Together with other indicators, weight will allow you to understand how the baby is developing and whether the fetus has any serious pathologies.

How to calculate the estimated weight of the fetus?

In modern obstetrics, various methods are used to determine the weight of the child in the womb - using several formulas and ultrasound. It is imperative to calculate the approximate weight of the fetus in the last weeks of pregnancy in order to determine the tactics of childbirth.

When calculating weight using formulas, certain parameters obtained by measuring and weighing the expectant mother are used. According to the methods of Yakubova and Zhordania, the calculation is made according to the circumference of the abdomen and the height of the uterine fundus. The Bublichenko and Lankowitz formulas use the weight and height of the pregnant woman. How to calculate the weight of the fetus before birth is determined by the doctor in each specific case.

It should be remembered that the relationship between the parameters in the formulas was established through clinical and statistical studies. And the results obtained during the calculations depend on many individual factors and are averaged.

Calculate fetal weight using ultrasound

Ultrasound examination is a rather responsible and complex diagnostic method, with the help of which the gestational age is specified, the intrauterine development of the fetus is monitored in accordance with physiological norms, and the sex of the child is determined. During the entire pregnancy, 3 scheduled ultrasounds are performed.

The first study is scheduled at 12 weeks, then in the second and third trimester. Diagnostics during these periods helps to timely diagnose abnormalities in fetal development and take the necessary measures to eliminate the defects. Ultrasound allows you to most accurately calculate the approximate weight of the fetus, since in this case the weight of the uterus and amniotic fluid is not taken into account.

Modern ultrasound machines are already equipped with calculation programs that take into account even the smallest details of the study. However, this is only an approximate value; the exact weight of the child can only be known after his birth.

We calculate fetal weight using ultrasound data ourselves

1. According to Shepard:

Log(10) Fetal weight = -1.7492 + 0.166*(BPR) + 0.046*(FB) - (2.646*(FB+BPR)) / 1000.

2. According to Hadlock:

Log(10) Fetal weight = 1.3596 + 0.0064*(OG) + 0.0424*(CO) + 0.174*(DB) + 0.00061*(BPR)*(CO) - 0.00386*( Coolant)*(DB).

The examination data in the protocol is indicated in millimeters; it is important to convert it to centimeters.

BDP (in the ultrasound protocol indicated as BPD) - biparietal head diameter (the distance between the most distant points of the fetal head).

The coolant (in the ultrasound protocol - AC) is the circumference of the fetal abdomen.

OG (HC) - fetal head circumference.

DB (FL) - length of the femur.

But even in this case, possible deviations of the child’s weight from the actual weight are 200-300 grams.

Normal fetal weight

The range of normal weight values ​​for newborns is quite wide: the minimum value is not lower than 2.5 kg, and the maximum value is not higher than 4.0 kg. Low weight children are born in case of placental insufficiency, when the placenta for some reason could not cope with its functions. Also, a premature baby may be born weighing less than 2.5 kg if it deviates from the normal course of pregnancy.

Large children weighing more than 4.0 kg are at risk of obesity and diabetes mellitus even in the newborn period. Their health requires close attention even in adulthood. In both cases, hereditary factors have a significant influence on the child’s weight.

Knowing how to calculate the weight of the fetus allows the expectant mother to independently monitor the baby’s weight in order to promptly eliminate deviations in fetal weight from normal values. If low or too much weight threatens problems for the child, the doctor will immediately warn you about this. The most important thing is not to worry prematurely.

The choice of obstetric tactics depending on fetal weight

How to calculate the weight of the fetus is half the question. The most important thing is to determine which method of delivery to choose. If the approximate weight of the child is within the normal range or less, this allows birth through the birth canal.

When the baby's estimated weight is more than 5.0 kg, this is an indication for a planned cesarean section. Although there have been cases where such large children were born naturally with a favorable outcome. If the child’s weight is between 4.0 kg and 5.0 kg, then an individual approach to the situation is necessary. The decision must be made by the doctor, taking into account the woman’s height, the size of her pelvis and other factors.

Thus, fetal weight is of great importance for determining obstetric tactics for childbirth.

Let's sum it up

It's no secret that the health of a child depends entirely on the mental balance and health of the mother. In order for a mother to worry less about her baby, she must be sure that his development is proceeding normally.

Therefore, it is extremely important for her to determine how to calculate the weight of the fetus, which method of calculation is more reliable. Thanks to state-of-the-art equipment, calculating mass using ultrasound is the most accurate method. Today, such an examination is quite accessible and has many advantages.

The most important thing is not to worry about trifles. And may you have a healthy and strong baby!