During 9 months of pregnancy, a woman undergoes at least 3 mandatory ultrasound examinations, or ultrasound screening. The first examination is carried out at approximately 11 weeks, then at 19 and 30 weeks. The first two screenings are aimed at detecting malformations of the embryo, and during the third, the weight of the fetus can be calculated using ultrasound.
Every doctor strives to find out the size of the unborn child, because this is an indicator of the correct development of the fetus. Birth weight depends on several factors: the health of the mother, the intensity of blood circulation and the condition of the placenta, as well as genetic predisposition. Doctors note that the normal weight of a newborn is from 2.8 to 4 kg, and boys are often born larger than girls.
Using diagnostic indications
Determining the weight of the fetus by ultrasound is possible only after the 11th week of pregnancy. For more early stages this diagnostic method does not provide all the necessary parameters for calculation. Doctors use special formulas or programs that are built into ultrasound machines. To determine how much it weighs unborn child, you can use a special calculator program or tables of correspondence between ultrasound parameters and the expected weight of the child.
The parameters necessary for calculation must be indicated in the ultrasound examination protocol:
- gestational age in weeks;
- fronto-occipital size (LZR, FOD);
- head circumference (OG, HC);
- head diameter, or biparietal size (BPD, BPD);
- abdominal girth (OJ, AC);
- femur length (FBL, FL).
For a more accurate calculation, the sizes of the bones of the lower leg, forearm and shoulder are also used. It is enough to enter the parameters into the program, and it will calculate the estimated weight of the fetus and display the result. Errors are possible due to the fact that different calculators can be programmed to match the parameters to the weight of the fetus differently. The calculation results obtained independently are for reference only, and only a doctor can make conclusions about the health of the fetus.
Without ultrasound results - using a calculator
You can calculate the weight of a baby in the womb without an ultrasound. To do this, you only need two criteria: abdominal girth and uterine fundus height. These measurements are taken by a gynecologist during each scheduled inspection. The measurement results are entered into the pregnant woman’s medical record.
In the simplest case, the estimated weight of the fetus is equal to the product of these parameters +/-200 g. However, doctors advise using this formula only towards the end of pregnancy. At earlier dates, calculation using this method gives a large error.
Child weight table - norm by week
Estimate approximate weight fetus can be measured using a table of weight norms by week.
| A week | Fruit weight, g | A week | Fruit weight, g |
|---|---|---|---|
| 7 | 1 | 25 | 650-700 |
| 8 | 1,5-2 | 26 | 750-850 |
| 9 | 3-4 | 27 | 800-900 |
| 10 | 4-5 | 28 | 950-1100 |
| 11 | 6-8 | 29 | 1000-1200 |
| 12 | 9-13 | 30 | 1100-1300 |
| 13 | 14-20 | 31 | 1300-1500 |
| 14 | 21-25 | 32 | 1600-1800 |
| 15 | 30-50 | 33 | 1900-2000 |
| 16 | 40-60 | 34 | 2100-2300 |
| 17 | 50-100 | 35 | 2300-2500 |
| 18 | 140-180 | 36 | 2500-2700 |
| 19 | 200-250 | 37 | 2800-3000 |
| 20 | 220-270 | 38 | 3000-3200 |
| 21 | 280-350 | 39 | 3100-3400 |
| 22 | 400-420 | 40 | 3200-2600 |
| 23 | 460-550 | 41 | 3300-3700 |
| 24 | 550-600 | 42 | 3500-3800 |
An exact match of results is not always possible. A deviation of the calculated parameters from the gestational age of two lines in both directions is considered normal.
How to gain weight for your baby during pregnancy
If the fetus weighs more than normal, the doctor must immediately take measures that will allow the mother to carry and give birth large child without complications. High weight may be an indicator of poor maternal nutrition during pregnancy and abnormal fetal development. In addition, in this case the risk of birth injury increases.
On the contrary, too little weight indicates a lack of essential nutrients in the diet and a delay in the development of the unborn child. If insufficient fetal weight is diagnosed, the woman is prescribed examinations: blood and urine tests, blood flow studies. Depending on the results, treatment is prescribed. A slight deficiency can be corrected by diet or taking special nutritional mixtures. If the deficiency is critical, the doctor decides on hospital treatment.
The greatest increase in a child's weight occurs in the last 1.5 months of pregnancy, so premature babies are often born with a significant lack of weight. For such children The best way recover quickly is breast-feeding. Mother's milk contains all the nutrients necessary for proper development. Therefore, when proper feeding By one year the child is already catching up with his peers.
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.
For expectant mother It is important 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, strengthens emotional connection between her and the child.
Modern medical equipment makes it possible 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. Within 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 one. little man. 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 g.
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 this case, even such a low-weight 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
| Week of pregnancy | |||
| minimum | average | maximum | |
| 7 | 0,8 | 1 | 1,2 |
| 8 | 1,5 | 1,8 | 2 |
| 9 | 3 | 3,5 | 4 |
| 10 | 4 | 4,5 | 5 |
| 11 | 6 | 7 | 8 |
| 12 | 9 | 11 | 13 |
| 13 | 14 | 17 | 20 |
| 14 | 21 | 23 | 25 |
| 15 | 30 | 40 | 50 |
| 16 | 40 | 50 | 60 |
| 17 | 50 | 75 | 100 |
| 18 | 140 | 160 | 180 |
| 19 | 200 | 225 | 250 |
| 20 | 220 | 245 | 270 |
| 21 | 280 | 315 | 350 |
| 22 | 400 | 410 | 420 |
| 23 | 460 | 480 | 500 |
| 24 | 550 | 575 | 600 |
| 25 | 650 | 675 | 700 |
| 26 | 750 | 800 | 850 |
| 27 | 800 | 850 | 900 |
| 28 | 950 | 980 | 1100 |
| 29 | 1000 | 1100 | 1200 |
| 30 | 1100 | 1200 | 1300 |
| 31 | 1300 | 1400 | 1500 |
| 32 | 1600 | 1700 | 1800 |
| 33 | 1900 | 1950 | 2000 |
| 34 | 2100 | 2200 | 2300 |
| 35 | 2300 | 2400 | 2500 |
| 36 | 2500 | 2600 | 2700 |
| 37 | 2800 | 2900 | 3000 |
| 38 | 3100 | 3150 | 3200 |
| 39 | 3200 | 3300 | 3400 |
| 40 | 3200 | 3400 | 3600 |
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.
Every doctor observing a pregnant woman strives to determine the approximate weight of the unborn child based on ultrasound results. To calculate this important indicator of the healthy development of the baby in modern obstetrics there are special formulas and calculator programs. Using the results of an ultrasound examination, you can calculate the approximate weight of the child (BW) and even the exact day of conception.
Fetal weight is an important value, the determination of which gives the doctor an idea of the correct development of the fetus. Also, these indicators make it possible to determine a large pregnancy and take timely measures for successful pregnancy and subsequent delivery.Fetal development norms
The normal weight of newborns ranges from 2800 to 4000 g. This indicator depends on a number of factors that, to one degree or another, influence the size of the unborn baby:
- genetic programming;
- the woman's health status;
- level of uteroplacental circulation.
The absolute increase in a child's weight each week depends on his increasing consumption of oxygen and nutrients. These needs are provided by the rapidly growing placenta. So, at the 16th week of pregnancy, the normal increase in weight is 80 grams. per week, and after 26 - almost 200 grams. in Week. After 37 weeks, the intensity of the increase decreases significantly, this is explained by the development of the placental aging process. Premature aging of the placenta slows down the supply of all necessary substances to the developing baby, as a result of which development slows down. This leads to the birth of children with insufficient physical development.
Obstetricians-gynecologists, based on many years of practice, note several natural facts:
- the size of the newborn depends on the height of the mother: the taller the woman, the larger the child;
- children of women giving birth for the first time are smaller than children of mothers with repeated pregnancies;
- male baby 150 - 200 grams. larger than a woman's.
Certain illnesses in a pregnant woman can cause the baby to gain abnormal weight. This pathology often occurs if the mother has diabetes. The main reason for the formation of excess fat is the increased level of insulin in the child’s blood.
Principles for calculating weight based on ultrasound results
- the total size of the embryo, i.e. the fertilized egg is measured in diameter, including all its membranes;
Calculation formulas consist of a large number of parameters that can be determined using ultrasound only after the 11th week of intrauterine development. Parameters for calculation:
- pregnancy period, indicated in weeks;
- fronto-occipital dimension (FOD);
- head circumference (HC);
- head diameter (BPD);
- abdominal circumference (AC);
- Femur length (FL).
You can obtain the necessary parameters for calculating the weight of the fetus only after the 11th week of pregnancy. A special formula is used In some cases, for a more precise calculation, additional indicators are used - the size of the bones: lower leg, forearm and shoulder. These characteristics are required to be indicated at the second planned ultrasound. Calculation based on ultrasound results is carried out using various programs that are available on certain Internet portals. Gynecologists use special formulas and tables to calculate the weight of the unborn baby.
Calculating mass using ultrasound readings
To independently determine your weight, it is not necessary to use calculator programs. You can use special tables containing PMP values.
To estimate the approximate weight of the baby, it is enough to find the readings of the corresponding parameters in the table:
| A week | Fruit weight, gr. | A week | Fruit weight, gr. |
|---|---|---|---|
| 7 | 1 | 25 | 650 - 700 |
| 8 | 1,5 - 2 | 26 | 750 - 850 |
| 9 | 3 - 4 | 27 | 800 - 900 |
| 10 | 4 - 5 | 28 | 950 - 1100 |
| 11 | 6 - 8 | 29 | 1000 - 1200 |
| 12 | 9 - 13 | 30 | 1100 - 1300 |
| 13 | 14 - 20 | 31 | 1300 - 1500 |
| 14 | 21 - 25 | 32 | 1600 - 1800 |
| 15 | 30 - 50 | 33 | 1900 - 2000 |
| 16 | 40 - 60 | 34 | 2100 - 2300 |
| 17 | 50 - 100 | 35 | 2300 - 2500 |
| 18 | 140 - 180 | 36 | 2500 - 2700 |
| 19 | 200 - 250 | 37 | 2800 - 3000 |
| 20 | 220 - 270 | 38 | 3100 - 3200 |
| 21 | 280 - 350 | 39 | 3200 - 3400 |
| 22 | 400 - 420 | 40 | 3200 - 3600 |
| 23 | 460 - 500 | 41 | 3300 - 3700 |
| 24 | 550 - 600 | 42 | 3500 - 3800 |
An exact match of the parameters with the gestational age is not always possible; minor deviations are allowed, since the tables provide average values of the indicators. A difference in values in the range + - two lines is considered acceptable.
Calculation without ultrasound results
Changes in fetal weight can be detected without ultrasound using simple data. You will need to find out the girth of the abdomen and the level of the fundus of the uterus You can find out the approximate weight of the baby without ultrasound results. Before an ultrasound at 32 weeks, a formula is successfully used that uses only two parameters: the level at which the fundus of the uterus is currently located and the girth of the pregnant woman’s abdomen. These indicators are measured and recorded during each mandatory appointment with the gynecologist. There are formulas in which the calculation is carried out taking into account the physique of the expectant mother. In this case, the “Soloviev index” is used - the length of the circumference of the wrist joint at the narrowest point.
Calculation of gestational age based on ultrasound results
Using ultrasound diagnostics, the basic physical characteristics of the baby are calculated, and the exact timing of pregnancy is determined. Typically, the estimated date of fertilization of the egg or the day of the last menstrual bleeding is used to calculate the period. The most accurate computational method is the one based on the fetal length, since this characteristic depends little on individual developmental characteristics.
These figures cannot be accurate; everyone knows that children can be born weighing 2500 or 4500, and are only indicative.
The normal weight of the fetus is almost the same for all women in the early stages, but as the duration of pregnancy increases, the individual difference becomes greater. However, before giving birth, everyone really wants to know for sure whether the baby is large; how the birth will proceed depends on this.
Determining fetal weight using external measurements
Obstetricians-gynecologists have special calculation formulas that allow you to estimate the size, weight and size of the fetus in late pregnancy. You can independently calculate the weight of the fetus at 32 weeks and later using simple calculations. They are very inaccurate, for this reason do not rely too much on the result.Basic formula for fetal weight:
Coolant x VDM
Multiply the abdominal circumference by the height of the uterine fundus (in centimeters). For example, the weight of the fetus at 33 weeks in a woman with an abdominal circumference of 86 cm and a fundal height of 33 cm will be, according to this formula, 2838 grams, +/- 200 grams. However, many things can affect these calculations, for example, body type, amount of amniotic fluid, and the position of the baby in the uterus.
To clarify the result, the weight of the fetus is calculated using two additional formulas:
Coolant + VDM x 100
The sum of the abdominal circumference and the height of the uterine fundus must be divided by 4 and multiplied by 100, in the previous example it turns out (86+33)/4*100 = 2950 grams.
The third formula takes into account the woman’s physique; the so-called Solovyov index, wrist circumference, is used. If it is more than 16 cm, 12 cm is deducted, if less than 16 cm, 11 cm is deducted.
(VDM - 12 or 11) x 155
The height of the uterine fundus, from it you need to subtract a coefficient (11 or 12) and multiply by 155, we get the weight in the previous calculation version of 3255 or 3410 grams, depending on the Solovyov index.
All results obtained from three formulas must be added and divided by three. It is clear that the accuracy of such calculations leaves much to be desired.
Fetal weight according to ultrasound
You can most accurately calculate the estimated weight of the fetus using ultrasound; measurements taken using ultrasound allow you to calculate the weight with great accuracy, while at the same time you can find out the correspondence of individual parameters to the gestational age.The ultrasound tables, which indicate the normal weight of the fetus by week during ultrasound, are very voluminous; we have compiled them into a service that will allow you to find out the child’s weight and height by simply entering data from the ultrasound examination protocol.
In order to get results, you need to at least have this protocol in hand.
You will need:
Know your gestational age in weeks BPR, this is the biparietal head size, you can also use LZR, fronto-occipital head size or baby’s head circumference (CH).
- OZ – the circumference of the child’s abdomen
- DlB, child’s thigh length
- DGrK – diameter of the child’s chest
To calculate, all fields must be filled in; if your protocol does not indicate abdominal circumference or chest diameter, you can substitute chest diameter or abdominal circumference, respectively.
Determining fetal weight by ultrasound does not depend on the amount of amniotic fluid, the position of the fetus in the uterus, or even the number of fetuses. Calculation of fetal weight by ultrasound is closest to the actual weight of the child at birth.
How to interpret the results? So, you calculated the weight of the fetus, or looked at the table, or found out using an ultrasound. And you see that it does not correspond to what was expected.
The fetal weight norm by week may not correspond to your calculations, either up or down, and the longer the pregnancy, the greater this difference may be.
In the early stages of pregnancy, the approximate weight of the fetus may be less or more than calculated only in cases where you made a mistake with the gestational age. Subsequent fetal weight gain depends on heredity, the condition of the placenta, and other factors. Before birth, normal fetal weight fluctuates widely, and 2500 and 4500 may be normal.
What determines the weight of the fetus?
From heredity
- on the nature of nutrition, health status and bad habits of the mother
- on the peculiarities of the course of this pregnancy
- on the number of fruits.
In case of twins, the lag in fetal weight begins at approximately 20 weeks, and this trend continues until childbirth. The weight of twins at birth is always less than normal by about 1-2 weeks, in relation to the indicators given by the table of fetal weight by week. Now you know how to determine fetal weight during pregnancy, you can always use the fetal weight formula, or you can use our fetal weight calculator using ultrasound.
Fetal weight calculator
The size of the baby largely determines how the birth will proceed, so calculating the weight of the fetus for many expectant mothers becomes almost a priority task. Obstetricians and gynecologists use several formulas that allow them to calculate the expected. It is worth noting that the data from such calculations are relative, since they depend on many features, including the anatomical structure of the mother, the amount of amniotic fluid, the position of the fetus in the uterus, etc.
Formulas for determining weight:
- Coolant x VDM
In this formula, the main quantities are the abdominal circumference and the height of the uterine fundus. So, for example, if at 32 weeks the abdominal circumference is 84 cm, and the second indicator is 32 cm, then the approximate weight of the fetus is 2688 g. It is worth repeating once again that the results of such calculations are relative, and the error can be up to 200-300 g.
- (coolant + VDM)/4 x 100
This formula also allows you to calculate the weight of the fetus during pregnancy. To do this, two indicators (abdominal circumference and height of the uterine fundus) must be added, divided by four and multiplied by one hundred. So, with the given parameters, the weight of the fetus will be 2900 g.
- (VDM – 12 or 11) x 155
The third formula shows how to calculate the approximate weight of the fetus, taking into account the woman’s physique. According to Solovyov’s formula, a certain index is subtracted from the height of the uterine fundus (12 if the woman’s wrist circumference is more than 12 cm, 11 if less), and then the resulting number is multiplied by 155. As a result, for this example, the weight of the fetus will be 3100 or 3255 gram depending on the body structure of the expectant mother.
Determination of fetal weight by ultrasound
The most accurate data can be obtained by calculating the weight of the fetus using ultrasound. An ultrasound examination allows you to determine not only the weight of the baby, but the correspondence of its individual sizes to the gestational age. In order to calculate, there is a special calculator. If you enter all the ultrasound examination data, you can get a result that is closest to reality.
By making calculations using various formulas and taking into account the results of ultrasound, you can calculate the most accurate weight of the fetus at birth. It is worth remembering that each organism is individual, so if the results obtained are higher or lower than normal, it is too early to panic. As a rule, the norms can be strictly applied only to the first half of pregnancy, when the fetus is still very small, while in the third trimester the error can reach 500 g.
