Many expectant mothers are very interested to know how their baby is developing. After all, its growth and changes turn out to be a kind of secret. The fetus is hidden inside the body of the mother, and she can see it only after childbirth. But far from idle curiosity is pushing women to find out how tall and weight their children are. The size of the fetus can tell a lot about its health and development, and also allow you to more accurately determine the duration of pregnancy.
How to find out the size of the fetus
The most common method that allows you to evaluate several measurements of the baby’s body and its weight is ultrasound. The fetus measures many parameters. For example, BDP, that is, the biparietal size of the head, is the distance from one parietal bone to another. In fact, this is the width of the head. This is just one of the parameters that allows you to estimate the approximate body weight. In addition to it, the circumference of the abdomen and the length of the femur are taken into account. Up to 28 weeks, BDP allows you to determine the gestational age to the nearest week. Later, the child’s head grows at an individual pace, so the accuracy of the calculation for this parameter is reduced.
Embryo growth is measured excluding legs. This KTR is the coccygeal-parietal size. The legs are bent, so the most reliable result is obtained when measuring the head and body. When measuring the fetus, doctors take into account the proportionality of all sizes. If not a single dimension is strongly out of proportion, the baby develops correctly.
In the later stages, important information about the size of the fetus is carried by the circumference of the abdomen and the height of the bottom of the uterus. This also allows you to roughly estimate the weight of the baby. For this, from the middle of the last century, there are special mathematical formulas.
Formula Jordania
In order to use this formula, you need to know the circumference of the abdomen of a pregnant woman and the height of the bottom of the uterus. Usually all this information is on the medical record. The stomach is easy to measure with a centimeter tape. But the height of the bottom of the uterus for calculations can be taken as an average of weeks. The weight of the fetus can be obtained by dividing the girth of the abdomen by the height of the uterine fundus.
True, sometimes to clarify these calculations, coefficients are introduced, which include the weight of the mother, the circumference of her wrists. This is due to the fact that the size of the abdomen can depend not only on the complexion of the baby, but also on the physique of the woman and her body fat. The thickness of the wrist speaks about the structure of the bones of a woman and allows you to evaluate her physique.
Formula Lankovitsa
This is a more accurate formula that takes into account much more indicators. To get the result, it is necessary to add the height of the pregnant woman in centimeters and her weight to the girth of the abdomen and the height of the uterine fundus. The resulting amount is multiplied by 10. True, and this method of calculation has errors. In 25% of cases, he is mistaken for 200, or even 500 g.
Duration and errors
In the early stages, for example, in the first trimester of pregnancy, noticeable deviations in the weight of the fetus by weeks with the correct structure of his body may indicate that the term is determined incorrectly. Based on this, the idea of the gestational age is usually clarified. After all, initially it is calculated in two ways.
The true gestational age is determined from conception. But not all women know the date of ovulation. But almost everyone remembers the start date of the last menstruation. This is where the obstetric period is considered. This is a gestation period that exceeds the real time of gestation by 2-3 weeks. Most often, ovulation occurs exactly 2 weeks after the start of the cycle. True, both the duration of the cycle in women and its other individual characteristics affect when conception actually occurs.
What determines the weight of the fetus
The weight of the fetus by week of pregnancy at the very beginning is usually the same for everyone. The more developed the fetus becomes, the more individual differences appear in it. Healthy full-term babies are born very different, sometimes their weight can vary by one and a half to two kg. In any case, children with a weight of 3 kg and 4.5 are both normal.
The weight of the baby may depend on the complexion of the parents. Genetics determines the physique of a child, and a large baby can be born to large parents. Moreover, with a high probability the baby's weight will be close to the weight of dad and mother at birth. So that the norms of fetal weight for weeks of pregnancy exist, but they should not be strict and always have some variation.
Low weight
But there are many other factors. Severe deviations from the normal weight of the fetus by weeks may indicate pathologies. Diseases and bad habits of a mother affect the body weight of the baby. Underweight can be a dangerous sign of a missed pregnancy or observed with a decrease in immunity.
In addition, this can be observed with hypoxia. A lack of oxygen is dangerous for the fetus, subsequently it can lead to pathologies in the brain, increased intracranial pressure.
Heavy weight
Excessively heavy weight is far from always a reason for joy that a hero will be born soon. Sometimes this can be observed with diabetes in the mother. Other causes of fetal overweight are swelling with elevated bilirubin levels. This can be associated with a dangerous disease - hemolytic disease of the newborn. Most often, this disease is observed in Rh conflict. It can lead to many pathologies in the work of the baby's body, for example, brain damage, which can even lead to mental retardation.
Improper nutrition of the mother leads to the fact that the baby has a large fat layer, but at the same time lacks useful substances. This is also not the best way to affect his body.
The reason for the birth of a large baby can be the individual characteristics of the mother's body and the course of her pregnancy. For example, a large, well-developed placenta supplies the baby with more nutrients and accelerates its growth.
The birth of an excessively large child can be dangerous, because it is more difficult for him to go through the narrow birth canal, therefore, the likelihood of injuries in the child increases. For the mother, this can also threaten Caesarean section or episiotomy.
Multiple pregnancy
Not only diseases and pathologies affect the change in fetal weight by week. An important factor is the number of fetuses in the womb. Usually the more of them, the lower the weight of each of them. After all, to carry out several large babies would be an impossible task for the mother's body! It is necessary to provide nutrition to all at once, and the place in the uterus is limited.
Therefore, with multiple pregnancy, babies are often born prematurely. If twins still have a chance to be born later than 37 weeks, then with more babies they are born even earlier. True, these children with small stature and weight can be full-term and have fully formed symptoms characteristic of a healthy baby. For example, they have no structural features of the ears, genitals, the navel is in the middle of the abdomen, and not lower. In special cases, for example, when there are as many as five fetuses, they can be born premature, for example, at 26 weeks with a weight of 1 kg.
First trimester
The weight of the fetus by week begins to be calculated only from the middle of the first trimester. The fact is that the embryo is too tiny to be able to estimate this parameter with sufficient accuracy. For example, at 8 weeks, the embryo weighs 1.5 g. To make it easier for the mother to imagine what size and shape the body of her unborn child has, sometimes clear comparisons are made with berries, nuts, vegetables. For example, at 8 weeks, the embryo weighs and bends like a cashew nut. At the 11th week, its weight reaches 10-15 grams. Depending on the term, the baby will add a few tens, and then hundreds of grams per week.
Second trimester
This is the interval from 13-14 to 26 weeks. The norms of the weight of the fetus by weeks in the second trimester suggest that it was during this period that he turned from a tiny creature into a little man, whose weight can reach 850-1000 g and which has pronounced individual facial features. The mother’s stomach during this period increases and becomes noticeable. Weight gain in a pregnant woman far exceeds the weight of the fetus, for example, may be 6-7 kg. This should not be confusing. The uterus grows with the child, it is filled with amniotic fluid, in which the baby is still moving quite freely. The volume of blood of the mother also increases. In addition, the fat layer is also growing, which protects the stomach from injuries and cold, and is also a reserve for the upcoming breastfeeding.
At 24 weeks, the weight of the fetus is from 550 to 750 g. Is it a lot or a little? If we compare this mass with the body weight of a newborn baby, then not so much. But if you remember that once the baby was a fertilized cell ... Almost half of the pregnancy remains before the birth, but if the baby is born at this time, it will be considered a premature birth, and not a miscarriage. Thanks to modern medicine, such crumbs have a chance of survival. True, they are small.
Third trimester
This is the time from 27 weeks to birth, which usually occurs at 40 weeks. The baby’s weight increases the fastest, by hundreds of grams per week. On the other hand, the fastest growth relative to the previous one occurred in the first trimester. The weight of the embryo during this time has increased hundreds of times compared with the weight of a tiny embryo. Now it is increasing by only 3-5 times.
This is due not only to the active growth of the child’s body, but also due to a significant increase in body fat. You may notice that premature babies look thin and have red wrinkled skin. A baby born on time is much more plump, and his skin is smoother. Fat not only contains a supply of energy, but also serves the purpose of thermoregulation. First of all, it saves the child from hypothermia. Of course, when it comes to body fat within normal limits. Overweight babies can have health problems. The weight of the fetus at 29 weeks is from 1300 to 1500 g. And this is already a lot.
The weight of the fetus at 30 weeks is 1600-1650 grams. His growth will already be 40-41 cm - only a fifth less than at birth. This means that the baby still looks thin.
Ultrasound is usually prescribed at 32-34 weeks. The weight of the fetus at 32 weeks usually reaches 1800-1850 g.
Conducting research at this time is due to the fact that the baby usually already occupies the right position before birth - the vast majority is in the head presentation, when the head is pointing down, to the exit from the uterus. Determining the condition of the placenta, the height and weight of the fetus, the location of the pelvic bones make it possible to plan the birth.
The weight of the fetus at 37 weeks can range from 2500 to 2800 g. Children born before 37 weeks are considered premature if their weight reaches less than 2500 g and their height is less than 46 cm.
Birth weight
And finally, children born on time, that is, in the region of 40 weeks, or rather, from 38 to 42, on average have a weight of 3100-3400 for girls and 3400-3600 for boys. Toddlers weighing from 4 to 5 kg are considered large, and those who weigh more than 5 are giants. Typically, such children have a large height, for example 56 cm.
The most important thing is that the child becomes beloved and desired, then it will be possible to overcome any adversity associated with its small or too heavy weight. And mothers during pregnancy are best to eat healthy foods, but do not go on diets so that the baby receives all the substances necessary for the development of the body.