How to understand the biparietal size of the fetus. How and why is the biparietal head size (BDP) of the fetus measured?

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For monitoring intrauterine growth and the development of the child during pregnancy, several obligatory ultrasound examinations are carried out, which include fetometry - measurement of the size of the fetus.

Starting from the 1st trimester (when the embryo is already visualized), one of the mandatory parameters that are determined during fetometry is the biparietal head size or BDP.

BPR - what is it in the ultrasound protocol?

BDP is the size of the head from one parietal bone to another, measured in the transverse plane. To do this, the ultrasound doctor positions the sensor so that the fetal head is visible from above.

Usually the shape of the head is oval, closer to round. The size from the forehead to the back of the head is determined by a parameter called fronto-occipital size or LZR. The line that is perpendicular to the LZR will be the BDP of the fetus.

• We can say that in the transverse plane BDP shows the width of the fetal head.

BPR - what is it (photo)

The measurement is carried out in two ways: externally - externally and internally - externally. Their difference lies in the location of the points between which the measurement is made: they can be located either on the outer and inner edges, or on both outer edges of the parietal bones.

This must be taken into account when analyzing the data obtained and comparing them with those tables of norms for which measurements were carried out in a similar way.

Why do you need to measure BDP:

• In the period from the 13th (but possibly earlier) to the 22nd week, this parameter determines the gestational age with an accuracy of 5 to 10 days. After the 28th week, the reliability of this definition becomes questionable due to different individual fetus growth rates and genetic features, the appearance of "mobility" of the shape of the head;
• Together with parameters such as abdominal circumference and length femur, BDP indicates the estimated fetal weight at the time of the study, which is especially important before upcoming birth, as it determines the method of childbirth: independently or with the help of caesarean section;
• A dynamic change in this size indicates fetal growth, a normal increase in brain size;
• Is a marker of violations prenatal development fetus and birth defects development.

Fetal BPR norm by week (table)

For an indicator such as fetal BDP, the norm is very variable and is never represented by a single number. Nomograms (tables that compare the result) are compiled using percentiles, that is, options that can occur when normal development.

The 90th percentile means that this indicator occurs in 90% or less of all the subjects studied, the 50th percentile - in 50% or less, and the 10th, respectively, in 10% or less.

Fluctuations within percentiles are not a pathology. Often such nomograms are compiled for each region, even within the same country, which is associated with different ethnic and racial characteristics.

Therefore, the BDP measured in a fetus whose mother lives permanently in Moscow may differ significantly from the BDP of a fetus whose mother, for example, is from Makhachkala. To determine exactly what such a parameter as BDP gives, you need to use tables with regional standards or, if they are not available, then according to the principle of territorial proximity.

Table - Biparietal size fetal heads by weeks, mm(based on the internal-external measurement method, Moscow region)

a week	percentile
	10	50	90
13	21	24	28
14	24	27	31
15	29	31	34
16	30	34	37
17	35	38	42
18	38	42	47
19	40	45	49
20	44	48	53
21	47	51	56
22	49	54	60
23	53	58	64
24	56	61	67
25	59	64	70
26	62	67	73
27	65	70	76
28	68	73	79
29	71	76	82
30	72	78	85
31	74	80	87
32	76	82	89
33	78	84	91
34	80	86	93
35	82	88	95
36	84	90	97
37	86	92	98
38	87	94	100
39	89	95	102
40	90	96	103

What to do if BDP deviates from the norm?

Deviation from the norm, which was detected once, special significance does not have, if it does not differ from the normal indicator within 2-3 lines in the table.

To suspect any violation of the development of the child, it is necessary to fix the change in BDP several times in a row. For this, ultrasonic fetometry is carried out in dynamics, usually with an interval of 1-2 weeks.

Increasing head size

Macrocephaly or large head

1. Large head sizes may be due to hereditary factors. If big size head is detected in one of the parents, then no special events are carried out.

In this case, the attending physician must determine the possibility of independent vaginal delivery or choose a caesarean section for delivery.

• If the large size of the head in the fetus is not associated with hereditary features, it is necessary to exclude developmental anomalies.

2. Hydrocephalus is an expansion internal cavities brain, which contain cerebral fluid - cerebrospinal fluid. The volume and pressure of the fluid increases - the size of the head increases.

The causes of hydrocephalus can be a violation of the development of the fetal brain, infection for a period of 13 to 27 weeks, tumors, injuries, hypoxia, spina bifida (non-fusion of the vertebrae, resulting in spinal cord does not have a full-fledged bone frame).

The detection of hydrocephalus before the period of fetal viability (3rd trimester) raises the question of termination of pregnancy. If the fetus is already at a viable age, then karyotyping, tests for viruses, detailed ultrasound, and a consultation with a neurosurgeon on the treatment of the child after birth are carried out.

• With an increase in pressure in the ventricles, it is necessary to carry out early delivery and further prompt elimination Problems.

3. Macrocephaly can be observed in violation of the development of bone and cartilage tissue. Such a disorder is thanatoform dysplasia - congenital disorder skeletal development, which is associated with a lack of ossification.

It is possible to detect an enlargement of the head on ultrasound, its shape in the form of a trefoil, in the middle of the 2nd trimester. Another pathology, achondrogenesis, in which the production of cartilage tissue is disrupted, also leads to the development of macrocephaly.

• This condition is a defect incompatible with life.

Hyperplastic development or large fruit

1. In this situation, heredity can also be the cause, and the increase in the size of the fetus may be due to the family constitution. It is necessary to find out with what body weight father and mother were born, and also to determine their body type.

• The large size of the fetus affects the decision on the tactics of childbirth.

2. The second reason for a large fetus can be gestational diabetes, or diabetes pregnant. It is necessary to conduct urine and blood tests for sugar. On an empty stomach, in the blood, the level of this indicator in pregnant women is lower than usual, and is 5.0-5.8 mmol / l.

There should be no sugar in the urine. If changes are detected in the analyzes, as well as for all pregnant women between 24 and 28 weeks, it is necessary to conduct an oral glucose tolerance test with 50 g. glucose. The test is carried out without pre-training, Anytime. After taking the solution of glucose inside, after 1 hour, the amount of sugar in the blood is determined.

If this indicator is more than 7.8 mmol / l, further examination by an endocrinologist is necessary. The treatment for gestational diabetes is to special diet. If blood sugar is still elevated, insulin injections are given.

• Any tablet preparations to reduce sugar during pregnancy are contraindicated.

Head size reduction

Microcephaly or small head

1. As with the large head size, the small head in the fetus may be related to the small head sizes in the family. Such a feature does not require treatment.

2. Spina bifida is a developmental disorder of the spine, which can be indirectly suspected when the shape of the head changes like "banana" or "lemon".

Refers to such defects in which abortion is recommended if the fetus has not yet reached a viable age. In other cases, it is necessary to inform parents about possible manifestations this disorder after the birth of the child, such as - impaired movement and sensation lower extremities, chronic pain, incontinence of feces and urine, curvature of the spine.

• If pregnancy persists, it is necessary to determine the date and method of childbirth.

3. Intrauterine infection, which leads to damage to the embryo for a period of 3-12 weeks, can lead to the formation of malformations with a decrease in the size of the head. If the infection has occurred for a period of 28 weeks, the infection is severe and spreads, that is, it becomes generalized - there is a delay in the development of the fetus and the associated decrease in head size and BPD.

If you suspect infection the mother conducts a number of studies aimed at identifying the pathogen: PCR, detection of antibodies in the blood, smear microscopy, bacterial cultures to nutrient media.

Treatment depends on the type of pathogen and trimester of pregnancy. From 14-16 weeks on the background general treatment prevent placental insufficiency.

• In case of rubella disease up to 16 weeks and if malformations are detected, it is recommended to terminate the pregnancy.

Hypoplastic development or small fetus

1. Hereditary low weight in children in the family, asthenic type of constitution in parents. special measures not accepted at normal flow pregnancy.

2. Decrease in body size can be genetic diseases, such as triploidy, trisomy on chromosome 13 - Patau syndrome, on 18 - Edwards syndrome, or on 21 - Down syndrome, which lead to early symmetrical fetal growth retardation: that is, both the head and the body of the fetus have a discrepancy with the gestational age.

In each case, the trip is individual. Children who are born alive have severe organ malformations and their life prognosis is unfavorable - most die in the first year.

The exception is children with Down syndrome, who necessary treatment And social support able to have a fairly high quality of life.

Osteogenesis imperfecta - This genetic defect development, which leads to a group of diseases with a violation of the formation of bone and cartilage tissue. Has several types.

When conducting ultrasound, only 2 types can be detected: shortened, curved bones and multiple fractures; deformation of the head occurs when pressure is applied to the sensor soft bones skulls. Osteogenesis imperfecta type 2 is not compatible with life.

BDP is important when calculating the cranial index (CI, Y), which indicates the cessation of fetal development, its intrauterine death and approximate time finding a dead fetus in the uterus.

• Cranial index = BPR / LZRx100. If CHI is 83 or more, this is the norm.

After 4-5 days from the moment of death of the fetus, destruction occurs internal structures brain and a significant decrease in BDP: if CI = 64-74, then the death of the fetus occurred less than 3 weeks ago, if CI = 64, then the fetus is not viable for more than 3 weeks.

Changing the shape of the head outside the pathology

Brachiocephaly or short head

The increase in BDP in this case will not be due to a decrease in the volume of the head, but due to a decrease in the LZR, that is, a decrease in the distance between the forehead and the back of the head. The head is more rounded or flattened.

• Brachiocephaly is often associated with individual features. Often this shape of the head is noted among the inhabitants of the Caucasus, Asians.

Dolichocephaly or long head

With dolichocephaly, a decrease in BDP is not a sign of head reduction, but is due to an increase in LZR. The head has a more oval, elongated shape.

In the fetus common cause the formation of dolichocephaly is the gluteal or breech presentation. Normally, such a structure of the head is also genetically more characteristic of representatives of the Nordic and Mediterranean peoples.

In these cases, to understand true size heads use the cephalic index: BPR / LZR, which is normally 0.75 - 0.85. When extreme values ​​of the cephalic index are detected, the determination of the gestational age according to BDP is not carried out.

Fetal BPD by week (table)

In this publication, we will try to analyze the essence of the method for determining fetal BPD, what it is and how much importance It has this indicator. This abbreviation stands for biparietal size (BPD). This is the baby's head size.

He is very important indicator when monitoring the development of pregnancy, and indicates the normal development of the fetal brain.

BDP values ​​are constantly changing over the course of pregnancy, therefore a lot of attention is paid to this indicator.

What does BPR mean and what is it for?

With each mandatory and additional ultrasound, the fetal head is studied very carefully. After all, the development of the fetal brain the most important factor the correct development of the child and the course of pregnancy. After all, here is main body that affects the entire body. With correctly determined sizes of the baby's head, you can accurately determine how the development of the brain and the fetus as a whole is going.

An ultrasound specialist measures fetal BPD. A measurement is taken in the direction from temple to temple. If the doctor takes the wrong distance, does not take into account that the line connecting the contours of the temples should be clearly above the thalamus, then he can get far from correct results. Next, the fronto-occipital part is measured, which is measured from the forehead to the back of the child's head.

But the biparietal size is considered more important, because it helps to more accurately determine the gestational age. It is for this purpose that the BDP of the fetus is established. In addition, the measurement values ​​help to resolve the issue of the possibility independent childbirth. For example, if the baby's head is significantly more sizes birth canal, the child himself will not be able to pass them.

And then there is the need for a caesarean section. Although in most cases, the head has dimensions that allow the baby to be born naturally.

Is there a norm for the biparietal size of the fetal head?

After measuring the BDP on ultrasound, the doctor compares them with normal sizes. For such comparisons, tables have been developed that record the average values ​​of normal BDP for each week of pregnancy and allowable deviations.

Any table is given at least from the twelfth week, because it is impossible to measure before this period. The fetus is too small for this BPD measurement.

And because of this, ultrasound often makes mistakes. Here is an example of such a table with normal indicators can be found on the Internet.

Normal performance

BDP by week of pregnancy (table)

BDP (BPD) (mm)	Term in avg. (week)	Range hesitation (week)	BDP (mm)	Term in avg. (week)	Range hesitation (week)
17	10,6	9,6-11,5	58	23,5	22,7-24,4
18	10,9	9,9-11,8	59	23,8	23,0-24,7
19	11,2	10,2-12,1	60	24,1	23,3-25,0
20	11,5	10,5-12,4	61	24,4	23,7-25,4
21	11,8	10,8-12,7	62	24,7	24,0-25,7
22	12,1	11,1-13,0	63	25,1	24,3-26,0
23	12,4	11,4-13,3	64	25,4	24,6-26,4
24	12,7	11,7-13,6	65	25,7	25,0-26,7
25	13,0	12,0-13,9	66	26,0	25,3-27,0
26	13,3	12,3-14,2	67	26,3	25,6-27,4
27	13,6	12,6-14,5	68	26,7	25,9-27,7
28	13,9	12,9-14,9	69	27,0	26,3-28,0
29	14,2	13,2-15,2	70	27,2	26,6-28,4
30	14,4	13,5-15,4	71	27,6	26,9-28,7
31	14,7	13,8-15,7	72	27,9	27,2-29,0
32	15,0	14,1-16,0	73	28,2	27,5-29,4
33	15,3	14,4-16,4	74	28,5	27,9-29,8
34	15,6	14,6-16,7	75	28,9	28,2-30,3
35	15,9	14,9-17,0	76	29,2	28,5-30,8
36	16,2	15,2-17,3	77	29,5	28,8-31,3
37	16,5	15,5-17,6	78	29,8	29,2-31,8
38	16,8	15,8-17,9	79	30,6	29,5-32,3
39	17,1	16,1-18,3	80	31,1	29,8-32,8
40	17,4	16,4-18,6	81	31,6	30,0-33,3
41	17,7	16,7-18,9	82	32,1	30,5-33,8
42	18,0	17,0-19,2	83	32,6	31,1-34,2
43	18,5	17,3-19,5	84	33,6	31,6-34,8
44	19,0	18,2-19,7	85	33,7	32,1-35,3
45	19,4	18,5-20,0	86	34,2	32,7-35,8
46	19,7	18,8-20,4	87	34,7	33,2-35,9
47	20,0	19,2-20,7	88	35,2	33,7-36,1
48	20,3	19,5-21,0	89	35,7	34,2-37,1
49	20,6	19,8-21,4	90	36,4	34,7-38,1
50	20,9	20,1-21,7	91	37,3	35,3-39,1
51	21,3	20,5-22,0	92	38,1	35,8-40,1
52	21,6	20,8-22,4	93	38,9	36,9-41,1
53	21,9	21,1-22,7	94	39,7	37,6-42,1
54	22,2	21,4-23,2	95	40,5	38,3-43,1
55	22,5	21,7-23,6	96	41,3	39,6-44,1
56	22,8	22,1-23,7	97	42,1	39,6-45,1
57	23,2	22,4-24,0	98	42,9	40,3-46,1

To install yourself BPR norm, the same table used by the uzist will help. If you carefully study it, you can easily judge the dimensions that the doctor writes down in the conclusion. The table has three columns. In the first, the dimensions of the norm are given. In the second, the terms of pregnancy are assigned, and in the third, possible deviations from the norm. For example, with a period of 22 weeks, the size is 53 mm, deviations are possible from 21.1 m on the smaller side and up to 22.7 mm on the other.

What to do if BDP deviates from the norm?

BPD - ultrasound picture showing biparietal size

In case of detected BDP deviations, ultrasound should be repeated in a few days by another specialist and on a different device. If deviations persist, the doctor should evaluate all other fetal parameters. Maybe a very large baby will be born ?!

In addition, it must be taken into account that the rapid growth of parameters at the beginning of pregnancy is replaced by a slowdown in recent months. And it is quite possible that the large fruit that was supposed at first "will not take place."

It happens that the baby develops in jerks. This may be another reason for the deviation of indicators from the norm. As a rule, after a while the parameters become normal. If this does not happen, and BDP on ultrasound still shows deviations, then you need to contact the doctors.

Parameters with a strong deviation from the normal BPD indicate such pathologies of the fetal brain as: tumor, hernia, and others. Doctors can prescribe a course of therapy, or they can offer to resolve the issue of terminating a pathological pregnancy.

If, for example, the doctor sets the BDP and all other fetal parameters are less than the prescribed normal results and all other parameters of the baby, a diagnosis is established - intrauterine growth retardation. The reasons for this phenomenon may be various infections or chronic hypoxia, which appeared against the background of violations of the placenta.

If the diagnosis is confirmed, the woman is admitted to the hospital and an urgent course of therapy is prescribed to eliminate the causes of this phenomenon. At the same time, procedures are prescribed that improve blood flow in the placenta and improve oxygen supply and vitality. important substances to the child. Even small BDP parameters on ultrasound may indicate microcephaly.

Incorrect parameters indicate various pathologies fetal brain. Doctors may prescribe a course of therapy, or may suggest terminating the pregnancy.

In conclusion on the importance of diagnosing the size of the BPD

Expectant mothers during pregnancy are offered several times an ultrasound examination. After such an examination, the uzist doctor necessarily gives pregnant women a research protocol, which contains all the information about the baby, including the BPD.

If you pass such an examination in time, you can get rid of a lot of pathologies. Therefore, such examinations are strongly recommended for pregnant women. It will not bring harm, but there are a lot of benefits from fetal ultrasound.

Today, obstetricians and gynecologists use different ways to measure the presence of various abnormalities in the fetus. In order to accurately measure the gestational age of the expectant mother to the day, gynecologists use a special index called the biparietal head size of the fetus, it is he who is the most correct.

To make such a measurement, you need to conduct a special ultrasound examination, usually doctors carry it out, starting from 12 weeks and up to 28. This article will help to correctly measure this index and describe in detail all the indicators, taking into account various terms mother's pregnancy and fetal development, as well as tell the reader about all sorts of deviations.

Biparietal size of the fetal head is normal

To measure the BDP of the fetal head, you need to take the correct distance from one temple to another, but do not forget that the line that connects the contours of the parietal bones, in without fail should pass strictly over the thalamus. If you arbitrarily change this long-established rule, then the results of the study will be too distorted, and as a result, the gestational age will differ significantly from reality. At a certain period of pregnancy, their values, which are the norm, therefore, the longer the period, the more significantly the BDP indicator changes, but do not forget that at the end of pregnancy, growth slows down significantly.

Fetal BPD by week

• at 12 weeks, is 21 mm,
• at 13 weeks approximately 24 mm,
• at 16 weeks - 34 mm
• at 24 weeks - 61 mm
• at 32 weeks - 82 mm
• at 38 weeks - 84 mm
• and at 40 weeks - 96 mm.

The doctor evaluates the BDP, also taking into account the fronto-occipital indicators, for this all measurements should take place at the level of the legs of the brain, as well as the visual tubercles. Because these data change strictly in proportion to the time of pregnancy of the expectant mother. It is worth remembering that if the fetus is at 38 weeks of development, then its head changes shape significantly, so if there is a dolichocephalic configuration of the BPD of the baby's head, then the index will be less than normal.

Ultrasound during pregnancy BDP of the fetal head in normal and pathological conditions

Thanks to the use of BDP of the fetal head and other similar indicators in today's medicine, doctors are able to find and prevent various deviations in the development of the baby in advance, for example, such as: very big child, hydrocephalus or intrauterine development. If these indicators are slightly different from the norm, then you should not fall into despair, you just need to measure other indicators that will show the full picture. And if all parts of the body are evenly enlarged, then we can safely conclude that there will be a large baby. But if only the size of the head is enlarged, then you should start to worry, because the fetus is almost certainly diagnosed with hydrocephalus and caused it. intrauterine infection.

When a gynecologist observes BDP less than the prescribed norm and all other parameters of the baby are much less than those that correspond real term gestation, then a disappointing diagnosis is made - a delay in the development of the fetus in the womb. The reasons under such circumstances are different, for example, it can be an intrauterine infection, as well as chronic hypoxia, which arose due to placental insufficiency.

If such a diagnosis is fully confirmed, then the expectant mother is assigned emergency treatment, which is completely aimed at eradicating the causes harmful effects. Therefore, doctors prescribe a number of procedures that improve blood flow in the uterus and placenta, and also affect the fetus to the fullest and he received oxygen and all the necessary nutrients, through the use of drugs such as Curantyl for pregnant women, Actovegin and, of course, Pentoxifylline.

Doctors diagnose microcephaly if the fetal BDP and the fronto-occipital size are significantly reduced.

During pregnancy, future mothers are required to undergo an ultrasound scan several times, after which the ultrasound doctor must give them a protocol on the study, where he details all the information about the development of the baby. Here in it he indicates all important information, including even the most important parameter - biparietal head size (BDP). Why this is done, we will now tell you.

BPR - transcript

When a doctor conducts an ultrasound examination of a child, first of all, he spends all his time on fully examining the baby's head. The explanation for this is very simple: the brain is located in the head - the most important organ in the human body, it is he who fully influences the state of the entire fetus as a whole. Therefore, if you correctly measure the size of the head, then it is possible to assess the development of the brain, and for this there is BDP. In other words, the biparietal size is the width of the fetal head, which is measured from one temple to another.

Of course, in modern medicine this is not the only parameter, there is also a fronto-occipital size (LZR), it will be measured from the forehead itself to the back of the fetus. But still, BDP is the main one, because it determines the development of the fetus. His doctor tries to measure when future mom be between 12 and 28 weeks.

Also, doctors operate on BDP when they consider the possibility of a woman in labor to give birth to a baby herself without surgical intervention. Otherwise, a caesarean section is scheduled.

Biparietal head size - normal

When I evaluate BDP, I use specially designed tables that collect average data to estimate head size for a certain period in this way. In such a table, data are given in percentiles, which are needed for a special designation in medical statistics, that is, the average value is the 50th percentile.

When a doctor wants to use the data of this table, then, first of all, he finds its average value, and then completely determines extreme points proper development fetus. Consider this table using an example when the fetus is 12 weeks old and its BDP for this period is 21 mm, while the norm ranges from 18 mm to 24 mm. Therefore, in the aisles of such indicators, you should not worry, because the size of each baby is different and this is affected anatomical structure his body.

Fetal BPD in the table - deviations from the norm

Of course, these indicators may not always fall exactly within the boundaries. But this does not always indicate any pathology, and in order to fully convince the doctor who observes the pregnant woman, whole line various studies. If, when measured, all elements of the body are proportional, then we can conclude that the fetus is simply large. Sometimes it is observed with such parameters that the baby grows in leaps and bounds.

But such deviations do not always speak of good, in most cases this indicates problems with the development of the child. If the head is much larger established norm, then this may also indicate a tumor in the brain or hydrocephalus. In such circumstances future mother The doctor suggests terminating the pregnancy. If the brain is less than normal, then there is nothing comforting here either, because this indicates problems with the brain. In this case, the pregnancy is also terminated. If BDP is reduced in the third trimester, then this only speaks of intrauterine growth retardation, which is perfectly treated today.

During pregnancy, a woman has to repeatedly undergo an ultrasound examination, showing how well the fetus develops in the womb. To assess the condition of the baby, a number of indicators are used, one of which is the biparental size of the fetal head. In other words, the distance between the temples of the baby's head is measured, the results are compared by weeks.

BDP parameters change over the course of pregnancy, each week has its own rate of indicators. Active growth heads are observed in the first two trimesters of pregnancy, the indicator is most informative in the period from 12 to 28 weeks and allows you to determine the approximate date of birth.

The discrepancy between the biparental size of the fetal head and the gestational age may indicate intrauterine growth retardation, hydrocephalus, microcephaly and other anomalies in the development of the child.

But not always BDP deviations from the norm are caused by pathological conditions. If the size of the head is commensurate with the size of the arms / legs and the circumference of the abdomen, then it is likely that the baby will simply be born large. Conclusions about the condition of the baby and deviations in its development can only be made by a gynecologist after assessing all the parameters of fetometry of the fetus.

The value of measuring the size of the fetal head on ultrasound

The main parameters measured during the study are the dimensions of the skull, the length humerus, the length of the femur and the volume of the abdomen of the child. When determining the parameters of the skull, two values ​​are important: BPR (biparietal size of the fetal head) and LZR (frontal-occipital size). BDP means transverse dimension head, the distance between the temporal bones. LZR is measured from the occipital to the frontal bone and means the longitudinal size of the skull.

In relation to each parameter, special tables have been developed. They indicate the values ​​\u200b\u200bof indicators corresponding to a certain gestational age. BPR, LZR and other quantities have three meanings: average rate, its upper and lower bound. These indicators are developed for each week of pregnancy, starting from the eleventh. All values ​​measured by ultrasound are indicated in the complex, since with the normal development of the fetus they must be balanced with each other and proportional to a certain week of gestation.

BPR - transcript

During ultrasound Special attention is given to the study of the head of the baby. This is not surprising: the brain the most important body, the growth and development of which directly affect the condition of the fetus. BDP will help determine the size of the head, and hence the level of brain development. The biparietal size is a kind of "width" of the head, measured along the minor axis, from temple to temple.

In addition to BDP, the fronto-occipital size (LZR) is also determined - along the major axis, from the forehead to the back of the head. However, the biparietal size remains the main parameter: it is it that is used to determine the gestational age. With particular accuracy, this can be established in the period of 12-28 weeks.

The values ​​of the biparietal size of the fetal head of BDP are also important for determining the possibility physiological childbirth. If the size of the fetal head does not correlate with the size of the birth canal, a decision is made on a planned caesarean section.

In the BDP tables, fetal head size values ​​are presented as percentiles. In order to use such a table and determine the rate of fetal BDP by week, you need to find the value of the 50th percentile, the remaining values ​​\u200b\u200bdetermine the boundaries of normal readings.

More than normal

When the biparietal size (BDP) of the fetal head is greater than normal, this may indicate the following phenomena:

• heredity. If someone in the family also has a large head volume, then in this case, treatment is not required;
• large fruit;
• brachycephaly (short head) - the skull is smaller than usual;
• macrocephaly;
• hydrocephalus;
• disorders in the development of bone and cartilage tissue;
• swelling of the bones of the skull;
• brain tumor or brain herniation;
• diabetes mellitus in pregnancy.

Less than normal

The main reasons for which insufficient indicators of BDP of the fetal head can be recorded are:

• heredity. In this case, if at least one of the parents has a small head, then there is no cause for concern and no treatment is required;
• small size of the embryo;
• intrauterine growth retardation;
• genetic diseases;
• dolichocephaly (long head);
• violation of the development of the spine, bone and cartilage tissues
• pathology of brain development or complete absence some of its parts;
• intrauterine infection.

Conclusion

The full picture of ultrasound can only be assessed by a doctor. In turn, the doctor conducting the pregnancy compares the data of the study of the BDP of the fetal head with other studies, analyzes and complaints of the pregnant woman, which allows him to make the correct diagnosis and prescribe the appropriate treatment.