Fetal head circumference by week: table

For all women, pregnancy is a special life stage. At this time, the future mother experiences new sensations and on the other hand she learns her own essence. Simultaneously with positive emotions and fantasies about the future baby, the young mother has to undergo a lot of consultations and take many tests. Such visits to the polyclinic sometimes make you nervous. But tests are necessary to control the normal growth and development of the baby in the woman's tummy.

When you need ultrasound

When the future mother comes to see her doctor, she is explained the need and the timing of observations under the ultrasound machine. There are two types of ultrasound study: screening and selective studies. Screening is the mandatory examination of all pregnant women using ultrasound at certain times. Usually a planned ultrasound examination of the future mother takes place on the terms of 10 to 12 weeks, from 22 to 24 weeks, at 32 and 37-38 midwifery pregnancy week. When performing this type of examination, the size of the fetus is measured and their compliance with the norms, the gestational age, the condition of the uterus and the placenta. Selective research is appointed by the attending physician if there is a suspicion of a complication of pregnancy. In the case of determining the pathology of pregnancy, such examinations can be conducted an unlimited number of times.

Fetometry - what is it and why?

One of the important procedures is the fetometry of the fetus. When carrying out the doctor analyzes the size of the fetus and their compliance with the norm. The procedure is an ultrasound examination, the data of which the expert verifies with the tables of norms. Check helps in time to detect malformations and abnormalities in the development of the baby. When performing fetometry, the circumference of the fetal head is determined by weeks - the norm is an important indicator. For weeks, the doctor fixes the values of ultrasound and draws conclusions about the health of the baby. When a doctor ascertains smaller fetal sizes than those established for a given period, it is said about the slowing of fetal growth. If, within the course of pregnancy, a lag is observed for a couple of weeks, the doctors talk about a delay in intrauterine development. This delay can be caused by bad habits of the mother, internal infections, chromosomal abnormalities or placental insufficiency.

How does the circumference of the growing head of a normally developing fetus

The fetal head circumference for weeks is an important indicator of the development of the fetus in the womb of the mother. As you know, the head of the child in the abdomen of the mother grows unevenly. At the beginning of development, its size greatly exceeds the size of the body. And by the end of pregnancy the size of the fetus becomes uniform and proportional. If you track how the fetal head circumference varies for weeks, you can see that the greatest increase occurs in the second trimester. It is from 15 to 26 weeks of pregnancy that the head circumference of the baby grows by an average of 12-13 mm. This increase occurs every week. With further increase in gestation, the growth of the circumference of the head slows down. By the end of the third trimester - about a month before the birth of the baby - this figure is the most by 12-15 mm.

How to measure the head circumference of a crumb

In order to measure the circumference of the fetal head for weeks, regular diagnostics using an ultrasound device is used. The research is carried out by a specialist in several projections to obtain the most correct and accurate result. In addition to diagnosing the head circumference, the physician performs diagnostics of such fetometric parameters as biparietal (BPR) and sagittal size, hip bone length, abdominal circumference, fronto-occipital (LZR) size and others.

The table of norms used for diagnosis helps a specialist to determine fetal development and potential deviations. If the doctor finds significant deviations from the norm, the woman is offered to make an abortion.

Formula for calculation

The circumference of the fetal head for weeks is determined by the same principle as biparietal size: measured by such a method as computer planimetry, or by the formula. Pre-determined biparietal and LZR head size. The formula has the form: OG = 1/2 * (LZR + BPR) * 3.1416. This indicator is rarely used to calculate the weight of the fetus and does not depend on the shape of its head.

Value of the head circumference of the child

What can tell a doctor such an indicator as the circumference of the head of the fetus for weeks? The table of norms of this indicator has boundaries. If they are exceeded, this indicates a developmental disability. In this case, the main task of the physician becomes earlier the detection of deviations and their correction. For example, an increase in the circumference of the head may indicate a disease such as hydrocephalus. The disease manifests itself in the accumulation of fluid in the cavities of the ventricles of the brain. This process leads to an increase in the pressure inside the skull and, as a consequence, to a decrease in the volume of the brain. Immediately after birth, the baby is punctured. With the help of the procedure, remove the accumulated liquid and ease the child's condition.

Meaning of indicators for delivery

In most cases, the excess of parameters is attributed to the individual characteristics of crumbs. For example, if the parents are large, it is assumed that the child will also be large. As already mentioned, the table indicates the circumference of the head of the fetus for weeks of pregnancy. An increase in the indicator at the end of the gestation period can lead to problems in the generic process. For example, to rupture of the perineum. In this case, an episiotomy is done, that is, a small incision to facilitate labor.

Importance of the indicator

Thus, the determination of the head circumference indices at different terms of pregnancy and comparison of other indicators helps the doctor to timely reveal the pathologies in the development of the fetus, the rates of growth and development, as well as possible complications. A woman should not independently interpret or try to decipher the results of ultrasound diagnosis and draw conclusions about the health of the baby. The doctor takes into account multiple factors and observations, and only then makes an objective conclusion. It is important to remember that the development of each baby is individual and may not occur according to tabulated values.

32 weeks - why it is important

An important stage in ultrasound diagnosis is the period in the 32nd week of pregnancy. Approximately in this period the fetus takes the correct position for the process of childbirth - head down. The fetal head circumference (32 weeks gestation) is approximately 283-325 mm. This period of pregnancy is quite significant. A little baby in the tummy of my mother almost formed and even has eyelashes and eyebrows.

Fetal head circumference: table

As already mentioned, the first important ultrasound diagnosis the future mother spends at 10-12 weeks of an interesting situation. The table shows the data starting from the 11th week of pregnancy. The calculation takes place from the day of the last menstruation. Table data for the 10th, 50th and 95th percentiles are presented. Most often, doctors are guided by the 50th percentile, but the norm is considered fluctuations from 10 to 95. Percentile is the percentage that is below a certain number of percent in the sample. That is, the 50th percentile indicates that 50% of these values are below this level.

Of course, for every woman the state of a small miracle is more important than anything in the world. While the baby is still in the tummy, the only way to see it is the ultrasound. The importance of examining the parameters of the head circumference, height, weight and others is due to the need for constant monitoring of fetal development. Such monitoring not only helps the experienced specialist to correctly lead a pregnancy, but also soothes the expectant mother who wants to hold her crumb on hand as soon as possible.