The starting countdown of the origin of human life begins with the fertilization of an egg by a spermatozoon. This fateful meeting takes place in the ampullar part of the fallopian tube, where, in the process of fusion, an embryo appears, consisting of a single cell - the zygote. But even this cell already has a human-specific set of 46 chromosomes.
The zygote has two main tasks: to divide actively and to get to the uterine cavity as quickly as possible. An insufficiently active zygote can either die immediately, or, without getting into the uterus, develop as an ectopic pregnancy.
Development of the fetal egg
After 30 hours, the fertilized egg divides into two parts, each of which will also divide in two every day. Cells that are constantly increasing in number and size are called the fetal egg. The fetal egg enters the uterine cavity on the fourth day from the moment of fertilization, and is a collection of only 12 cells. Securely attached to one of the walls of the uterus, the fetal egg continues to divide even more intensively - by the end of the sixth day, there are more than a hundred cells in it.
At first, the fetal egg is a watery substance, which includes the developing embryo and the amniotic fluid surrounding it - a nutrient and protective environment. From the fifth week from the moment of fertilization, the fetal egg is already visualized by ultrasound.
Normally, the fetal egg has a round or oblong shape. A flattened or shapeless appearance may be evidence of genetic abnormalities in the fetus or a sign of uterine tone in a pregnant woman, other pathologies in the course of pregnancy.
The size of the fetal egg is one of the criteria for confirming pregnancy and determining its timing. So, for the first time it is detected on ultrasound no earlier than 5 weeks from the moment of conception, and its size is only 5-6 mm. Modern transvaginal sensors, due to their high resolution, can detect pregnancy even earlier - for a period of 4 weeks, when the size of the fetal egg is only 1 mm.
From the fifth to the tenth week of pregnancy, the size of the fetal egg changes as follows:
- 5 week - 5-6 mm;
- 6 weeks - 11 mm;
- 7 week - 19 mm;
- 8 week - 27 mm;
- 9 week - 35 mm;
- 10 weeks - 44 mm.
The range of time fluctuations can be up to 3 weeks, that is, in one woman, a fetal egg, 20 mm in size, is formed by the end of the sixth week, and in another, only by the beginning of the ninth. Therefore, the size of the fetal egg for gynecologists is not an indisputable and the only reliable indicator of the gestational age. With a minimum error, it is possible to determine only pregnancy in women with "classic" menstrual cycle in 28 days without gynecological diseases, other health problems.
Embryo size by week
Approximately at the sixth week, an embryo is determined inside the fetal egg during ultrasound diagnostics. From that moment on, it becomes the main and most reliable source for determining the gestational age.
The length of a 6-week-old embryo fluctuates within 3 mm, but, despite such microscopic dimensions, it is already a full-fledged born life, since you can listen to its heartbeat. The length of the embryo and its heart rate, in contrast to the size of the fetal egg, are less subject to variability. Therefore, the error in determining the gestational age for these indicators is only three days.
Regardless of the size of the ovum, the maximum length of a 6-week-old embryo is 55 mm. Up to 14 weeks, it grows at the following rates:
- 7 week - 8.9 mm;
- 8 week - 14.7 mm;
- 9 week - 21.9 mm;
- 10 week - 30.5 mm;
- 11 weeks - 40.4 mm;
- 12 weeks - 51.7 mm;
- 13 weeks - 64.3 mm;
- 14 weeks - 78.3 mm.
Determining the gestational age and the date of the upcoming birth by the size of the fetal egg and the length of the embryo is advisable only up to 12-14 weeks, that is, in the first trimester. After this time, the embryo moves to the next stage of development - the formation of the fetus. The most reliable data for diagnosing the timing of pregnancy are such data as the circumference of the head and abdomen, physical activity, heart rate, the formation of the circulatory system, limbs.
When conducting the very first ultrasound, which is done with a delay in menstruation and in order to accurately diagnose uterine pregnancy, you can see the fertilized egg. It was at this time, having seen this tiny formation on the monitor, the doctor already informs you that you will soon become a mother. In the photo you can see a fetal egg - a small oval formation. At an early stage, the embryo that will develop in the fetal egg is not yet visualized, but soon it will grow up and be clearly visible. An empty ovum is an egg without an embryo when pregnancy does not develop. The embryo is usually visible from the fifth week of pregnancy, but sometimes there are situations when the ultrasound doctor does not see the embryo even at this time, in which case a repeat ultrasound is prescribed. Very often, a repeated ultrasound shows both the embryo and the heartbeat. If after six to seven weeks the embryo is not visible, then, unfortunately, there is a high probability that the pregnancy does not develop.
Diameter of the fetal egg
Ultrasound assesses the average internal diameter of the fetal egg -SVD. Our table showsSVDin mm, typical gestational age for this sizeSVD(50 percentile), as well as possible normal fluctuations (terms of pregnancy for which such an indicator may be possibleSVD, 5th and 95th percentile). The diameter of the fetal egg is considered a variable value, which is why there is an error in determining the gestational age only by this fetometric indicator. The average error is 1.5 weeks. Only by the size of the fetal egg, they usually do not determine the gestational age, they always look in additionKTRdue to the smaller variability of this size. Please note that after 16 weeksKTRusually not measured, and when determining the gestational age, other indicators are guided.The embryo and the shell that surrounds it is the fetal egg. As the embryo grows, the size of the fetal egg increases by weeks, which can be observed during examination using ultrasound. But it should be remembered that the accuracy of studies in the early stages of pregnancy is low, and when a woman is diagnosed with a diagnosis, the possibility of error is not ruled out.
Formation of the fetal egg
The first stage of the cycle that the germ cell goes through is the release of the egg from the follicle. Usually 3-4 follicles mature, but only one egg during ovulation passes through the fallopian tubes of a woman.
The growth and development of a new life begins with the fusion of the egg and sperm. Immediately after ovulation and fusion, a protective sheath forms around the egg. This upper protective layer around the embryo will further develop into a fetal bladder containing amniotic fluid in the cavity.
In the early stages of pregnancy during ultrasound, you can see the formation of an ovoid shape of a small diameter. This is the fertilized egg. The first stage of its development is the morula, consisting of 12-32 blastomeres formed as a result of the division of the zygote, which turn into a compact ball.
As the cells multiply, the embryo continues to move through the fallopian tubes until it is fixed on the mucous wall inside the uterus. After that, the outer layer of the shell begins the production of hCG (chorionic gonadotropic hormone), which is one of the first indicators of a woman's pregnancy. All this time, the nutrition of the fetus is carried out at the expense of the internal resource of the egg. In the process of further development, the attachment site is transformed into the placenta. At this time, to prevent infection, a mucous plug forms, which closes the entrance to the uterus. This whole process takes about two days. If the embryo does not attach to the wall of the uterus, then along with menstruation at the end of the cycle, a miscarriage occurs, and often the woman does not even know that she was pregnant. On the next cycle, the egg is released from the follicle again, ovulation occurs, and the whole process is repeated again.
What does a fetal egg look like, structure:
- Villous membrane, chorion;
- Amnion (amniotic sac or water sheath);
- Embryo.
It is difficult to see exactly what a fetal egg looks like even with an ultrasound. Due to the small diameter, the embryo is difficult to detect inside the uterus if a woman is less than a month pregnant.
It happens that even at a period of 6-7 weeks, the embryo is not visible inside the egg - this may indicate an undeveloped pregnancy. An empty gestational sac is quite rare, and is often a symptom of a genetic disorder in a woman or her partner.
The study of the fetal egg
The diagnostic method by which the study of the life cycles of the fetal egg is carried out is called echography or, in other words, ultrasound diagnostics. It allows you to identify SVD, the average internal diameter of the fetal egg, and KTR, the coccygeal-parietal size of the fetus.
Usually, the doctor prescribes the first ultrasound for a woman at a period of 10 to 13 weeks of pregnancy. If necessary, diagnosis is carried out at 3-4 weeks. This is due to the fact that a fertilized egg is fully fixed inside the uterus only 10 days after conception. With the help of ultrasound, you can track the time of ovulation and the maturation of the follicle.
Do not worry that ultrasound will harm the fetus. Even at an early stage, radiation does not affect the health of the unborn child.
It is worth considering separately the 4th obstetric week of pregnancy, since it is during this period that ultrasound can be used to see the emerging life. In the first days of the fourth week of pregnancy, the fetal egg has a diameter of only 1 mm, and it is not possible to assess the details of the formation of the fetus. That is why an additional ultrasound is prescribed a few weeks after the first examination. However, after a couple of days, the size of the fetal egg will increase to 3 mm, and it will be possible to see the yolk sac, with which the embryo is fed until the umbilical cord appears. Toward the end of the fourth week, the diameter of the fetal egg increases to 4 mm, during this period vital organs begin to form: the heart, lungs, liver and pancreas. On the last day of this period, the diameter of the fetal egg is 5 mm, and during ultrasound it is already possible to detect an embryo whose size is only 1 mm. Literally in a day, the egg grows up to 6 millimeters.
The formula for determining the gestational age:
The average internal diameter of the fetal egg is + 35 (if its size is less than 16 mm) or 30 (if the fetus is more than 16 mm). For example, diameter 17+30=47 weeks.
Pathology of the fetal egg
When studying the fetal egg by echography, pathologies can be detected already in the early stages. The absence of an embryo inside the shell, an "empty egg" or anembryony, may indicate a non-developing pregnancy that will end in a miscarriage or a purge.
A picture in which a discrepancy between the size of the growing embryo and the egg is seen in the absence of a heartbeat may indicate the fading of the fetus, which also leads to a miscarriage.For example, if the embryo is much smaller than the shell or the size of the bubbles is too small for a given period, then a miscarriage will most likely occur at the end of the cycle. The most common cause is chromosomal changes at the time of conception, both congenital and caused by external influences. For example, a woman, unaware of pregnancy, takes pills, drinks alcohol or is exposed to other harmful influences, which leads to a serious pathology in the development of the fetus and miscarriage.
Deformation of the fetal egg is not always a pathology, and in most cases is caused by an increased tone of the uterus in the first period of pregnancy. Often, the tone is accompanied by small spotting and pain in the lower third of the abdomen.
This problem is solved with medication, pills are prescribed to reduce the number and intensity of uterine muscle contractions and hormonal pills to keep the fetus inside.
With detachment of the fetal egg in the case of a small area of the lesion, hormonal treatment is performed. For a woman during this period, bed rest in a hospital is mandatory.
An ectopic pregnancy is characterized by the fact that the fetal egg develops in an unintended place: in the fallopian tubes or ovaries. Of the manifestations, the main one is profuse bleeding. It is impossible to save such a pregnancy, since the growth and development of the embryo in fallopian tube leads to its rupture and serious consequences for the woman's health.
During screening at 12 weeks, the nasal septum is measured. In the event that the bone is less than 2.5 mm in length or is absent, doctors can establish a preliminary diagnosis: trisomy 21 chromosomes or Down's disease. In this case, the woman herself will be able to decide whether to continue the pregnancy.
In rare cases, two embryos are found in a fetal egg at once - this is not an anomaly, but a factor indicating the presence of twins. A similar situation occurs when two bubbles are found in the uterus of a woman at once. In the latter situation, the chorions of both membranes in the future form placentas, with the help of which each fetus feeds separately. In the first case, the embryos will be fed from one placenta. The detection of twins in the early period is often not confirmed, and the study gives a reliable result only at 6-7 weeks of pregnancy.
The size of the fetal egg by week
The fourth was discussed above. obstetric week. However, the development of the fetal egg lasts up to 8 weeks, and according to some sources up to 10, and in further periods of development, the embryo is called the fetus. Data on the stages of development of the embryo in each week can be seen in the table below. This table with detailed description of each stage of the development of the fetal egg will help a woman understand how the baby develops inside her uterus during this period. Rates of growth:
- Up to 15-16 weeks 1 millimeter per day;
- From 16-17 weeks 2-2.5 millimeters per day.
The size of the fetal egg by week, table:
Especially during this period of intrauterine development, the sixth week is important, since during this period the birth of digestive system, spleen and cartilage rudiments. When the size reaches 16 mm, we can say that the embryo has the rudiments of the stomach and esophagus, as well as 3 intestinal loops. By the end of the week, the fingers and muscle tissue are formed in the embryo.
For many women during pregnancy, the issue of internal growth and development of the child is very important. Such data can only be given by ultrasound in the early stages. The size of the fetus is calculated in conjunction with other measurements, as the fetus is in a comfortable position for him with his legs tucked in.
There are average norms for the size of a child on ultrasound, but it is worth knowing that this is individual and depends on many factors, including the genetics of the parents.
Fetal size by week of pregnancy
3 weeks.
On the initial stage development of pregnancy, the embryo is a small germinal vesicle. On ultrasound, its size in diameter is about 0.2 mm.
4 weeks.
The size of the embryo reaches 0.5 mm in diameter.
5 weeks.
The length of the embryo is from 1 to 1.5 mm. fertilized egg has 18 mm inner diameter.
The coccyx-parietal size (KTP) is 3 mm.
6 weeks.
The length of the embryo is about 4 mm. The inner diameter of the fetal egg is 22 mm.
KTR reaches 6 mm.
PHOTO: 6 weeks pregnant: fetal size by ultrasound
7 weeks.
The length increases to 1.5 cm. The embryo has a disproportionately large head. The inner diameter of the fetal egg is 24 mm.
KTR is 10 mm.
PHOTO: 7th week of pregnancy: fetal size by ultrasound
8 weeks.
It is from this time that ultrasound includes indicators of the weight of the fetus, which at week 8 is from 1 to 1.5 g.
The length of the embryo from the coccyx to the parietal region can reach 2.2 cm. It is the measurement of the parietal-coccygeal length that continues throughout pregnancy, since even after the fetus is fully formed, it cannot be measured from the crown to the heels (the natural position of the embryo is bent legs).
The inner diameter of the egg has an average size of 30 mm.
KTR is 16 mm.
Biparental head size (BDP) - 6 mm.
PHOTO: 8th week of pregnancy: fetal size by ultrasound
9 weeks.
Weight approximately 2 g. Length from the parietal region to the sacrum from 13 to 17 cm.
The fertilized egg has an internal diameter of 33 mm.
KTP - 23 mm.
BPR - 8.5 mm.
PHOTO: 9th week of pregnancy: fetal size by ultrasound
10 week.
Weight no more than 4 g.
The distance from the crown to the waist is from 27 to 35 mm.
The average size of the internal diameter of the fetal egg is 39 mm.
KTP - 31 mm.
BPR - 11 mm.
PHOTO: 10th week of pregnancy: fetal size by ultrasound
11 weeks.
The length of the fetus from the crown to the sacrum is about 55 mm. Weight reaches 7 g.
The inner diameter of the fetal egg is 47 mm.
KTP - 41 mm.
BPR - 15 mm.
From week 11, with the help of ultrasound, the approximate height and weight of the fetus is calculated. This requires measurements of the length of the thigh and the diameter of the chest.
Fruit size:
Fetal growth - 6.8 cm.
Thigh length - 6.5 mm.
The chest is 20 mm in diameter.
PHOTO: 11th week of pregnancy: fetal size by ultrasound
12 weeks.
The length of the fetus from the crown to the sacrum is from 70 to 90 mm.
Weight reaches 14-15 g.
The average value of the internal diameter of the fetal egg is 56 mm.
KTP - 53 mm.
BPR - 20 mm.
Fruit size:
Fetal growth - 8.2 cm.
Thigh length - 9 mm.
PHOTO: 12th week of pregnancy: fetal size by ultrasound
13 weeks.
The length of the fetus from the crown to the sacrum is 10 cm. The weight reaches 25 g.
The average value of the inner diameter of the fetal egg is 65 mm.
KTP - 65 mm.
BPR - 24 mm.
Fruit size:
Fetal growth - 10 cm.
Thigh length - 12 mm.
The chest is 24 mm in diameter.
PHOTO: 13th week of pregnancy: fetal size by ultrasound
14 weeks.
The length of the fetus from the crown to the sacrum is 11 cm. The weight can reach 43 g.
Baby head size:
BPR - 26 mm.
The perimeter of the skull is 80 mm.
Skull area - 510 mm2.
Fruit size:
Fetal growth - 12 cm.
Thigh length - 16 mm.
The chest in diameter is 26 mm.
PHOTO: 14th week of pregnancy: fetal size by ultrasound
15 weeks.
The length of the fetus from the crown to the sacrum is 11 cm. The weight can reach 70 g.
Baby head size:
BPR - 32 mm.
The perimeter of the skull is 90 mm.
Skull area - 675 mm2.
Fruit size:
Fetal growth - 14.2 cm.
Thigh length - 19 mm.
The chest is 28 mm in diameter.
PHOTO: 15th week of pregnancy: fetal size by ultrasound
16 weeks.
The length of the fetus from the crown to the sacrum is 16 cm. The weight can reach 85 g.
Baby head size:
BPR - 35 mm.
The perimeter of the skull is 102 mm.
Skull area - 860 mm2.
Fruit size:
Fetal growth - 16.2 cm.
Thigh length - 22 mm.
The chest is 34 mm in diameter.
PHOTO: 16th week of pregnancy: fetal size by ultrasound
17 weeks.
The length of the fetus from the crown to the sacrum is 17 cm. Weight is approximately 142 g.
Baby head size:
BPR - 39 mm.
The perimeter of the skull is 120 mm.
Skull area - 1080 mm2.
Fruit size:
Fetal growth - 18 cm.
Thigh length - 24 mm.
The chest is 38 mm in diameter.
PHOTO: 17th week of pregnancy: fetal size by ultrasound
18 weeks.
The length of the fetus from the crown to the sacrum is 20 cm. The weight can reach 200 g.
Baby head size:
BPR - 42 mm.
The perimeter of the skull is 126 mm.
Skull area - 1320 mm2.
Fruit size:
Fetal growth - 20 cm.
Thigh length - 28 mm.
The chest is 41 mm in diameter.
PHOTO: 18th week of pregnancy: fetal size by ultrasound
19 weeks.
The length of the fetus from the crown to the sacrum is 20-22 cm. The weight can reach 230 g.
Baby head size:
BPR - 44 mm.
The perimeter of the skull is 138 mm.
Skull area - 1450 mm2.
Fruit size:
Fetal growth - 22 cm.
Thigh length - 31 mm.
The chest is 44 mm in diameter.
PHOTO: 19th week of pregnancy: fetal size by ultrasound
20 weeks.
The length of the fetus from the crown to the sacrum is 25 cm. The weight can reach 280 g.
Baby head size:
BPR - 47 mm.
The perimeter of the skull is 144 mm.
Skull area - 1730 mm2.
Fruit size:
Fetal growth - 24 cm.
Thigh length - 34 mm.
The chest is 48 mm in diameter.
PHOTO: 20th week of pregnancy: fetal size by ultrasound
21 weeks.
The length of the fetus from the crown to the sacrum is 25 cm. Weight is from 360 to 370 g.
Baby head size:
BPR - 51 mm.
The perimeter of the skull is 151 mm.
Skull area - 1870 mm2.
Fruit size:
Fetal growth - 26 cm.
Thigh length - 37 mm.
The chest is 50 mm in diameter.
PHOTO: 21 weeks of pregnancy: the size of the fetus by ultrasound
22 weeks.
The length of the fetus from the crown to the sacrum is 27 cm. Weight is from 425 to 430 g.
Baby head size:
BPR - 54 mm.
The perimeter of the skull is 162 mm.
Skull area - 2190 mm2.
Fruit size:
Fetal growth - 28 cm.
Thigh length - 40 mm.
The chest is 53 mm in diameter.
PHOTO: 22nd week of pregnancy: fetal size by ultrasound
23 weeks.
The length of the fetus from the crown to the sacrum is 30 cm. Weight 500 g.
Baby head size:
BPR - 58 mm.
The perimeter of the skull is 170 mm.
Skull area - 2520 mm2.
Fruit size:
Fetal growth - 30 cm.
Thigh length - 43 mm.
The chest is 56 mm in diameter.
PHOTO: 23rd week of pregnancy: fetal size by ultrasound
24 weeks.
The length of the fetus from the crown to the sacrum is 30 cm. Weight 590 g.
Baby head size:
BPR - 61 mm.
The perimeter of the skull is 183 mm.
Skull area - 2710 mm2.
Fruit size:
Fetal growth - 31 cm.
Thigh length - 46 mm.
The chest is 59 mm in diameter.
PHOTO: 24th week of pregnancy: fetal size by ultrasound
25 weeks.
The length of the fetus from the crown to the sacrum is approximately 31 cm.
Weight from 700 g.
Baby head size:
BPR - 64 mm.
The perimeter of the skull is 194 mm.
Skull area -3072 mm2.
Fruit size:
Fetal growth - 32 cm.
Thigh length - 48 mm.
The chest in diameter is 62 mm.
PHOTO: 25th week of pregnancy: fetal size by ultrasound
26 weeks.
The length of the fetus from the crown to the sacrum is approximately 32-33 cm. Weight - 800 g.
Baby head size:
BPR - 67 mm.
The perimeter of the skull is 199 mm.
Skull area - 3260 mm2.
Fruit size:
Fetal growth - 33 cm.
Thigh length - 51 mm.
The chest in diameter is 64 mm.
PHOTO: 26th week of pregnancy: fetal size by ultrasound
27 weeks.
The length of the fetus from the crown to the sacrum is approximately 34 cm. Weight - 900 g.
Baby head size:
BPR - 68 mm.
The perimeter of the skull is 215 mm.
Skull area - 3675 mm2.
Fruit size:
Fetal growth - 35.5 cm.
Thigh length - 53 mm.
The chest in diameter is 69 mm.
PHOTO: 27th week of pregnancy: fetal size by ultrasound
28 weeks.
The length of the fetus from the crown to the sacrum is approximately 35 cm. Weight - 1000 g.
Baby head size:
BPR - 72 mm.
The perimeter of the skull is 218 mm.
Area - 3880 mm2.
Fruit size:
Fetal growth - 37 cm.
Thigh length - 55 mm.
The chest in diameter is 73 mm.
PHOTO: 28th week of pregnancy: fetal size by ultrasound
29 weeks.
The length of the fetus from the crown to the sacrum is approximately 37 cm.
Weight - 1150 g.
Baby head size:
BPR - 75 mm.
The perimeter of the skull is 225 mm.
Area - 4100 mm2.
Fruit size:
Fetal growth - 39 cm.
Thigh length - 57 mm.
The chest in diameter is 76 mm.
PHOTO: 29th week of pregnancy: fetal size by ultrasound
30 weeks.
The length of the fetus from the crown to the sacrum is approximately 37.5 cm.
Weight can reach 1400 g.
Baby head size:
BPR - 78 mm.
The perimeter of the skull is 234 mm.
Skull area - 4563 mm2.
Fruit size:
Fetal growth - 40 cm.
Thigh length - 59 mm.
The chest in diameter is 79 mm.
PHOTO: 30th week of pregnancy: fetal size by ultrasound
31 weeks.
The length of the fetus from the crown to the sacrum is 38-39 cm. The weight can reach 1500 g.
Baby head size:
BPR - 80 mm.
The perimeter of the skull is 240 mm.
Skull area - 4810 mm2.
Fruit size:
Fetal growth - 41 cm.
Thigh length - 61 mm.
The chest in diameter is 81 mm.
PHOTO: 31 weeks of pregnancy: the size of the fetus by ultrasound
32 weeks.
The length of the fetus from the crown to the sacrum is approximately 40 cm. Weight - 1700 g.
Baby head size:
BPR - 82 mm.
The perimeter of the skull is 246 mm.
Skull area - 5040 mm2.
Fruit size:
Fetal growth - 42 cm.
Thigh length - 63 mm.
The chest in diameter is 83 mm.
PHOTO: 32 weeks pregnant: fetal size by ultrasound
33 weeks.
The length of the fetus from the crown to the sacrum is 42 cm. Weight is 1800 g.
Baby head size:
BPR - 84 mm.
The perimeter of the skull is 255 mm.
Skull area - 5290 mm2.
Fruit size:
Fetal growth - 43.5 cm.
Thigh length - 65 mm.
The chest in diameter is 85 mm.
PHOTO: 33rd week of pregnancy: fetal size by ultrasound
34 weeks.
The length of the fetus from the crown to the sacrum is 42 cm. Weight is 2000.
Baby head size:
BPR - 86 mm.
The perimeter of the skull is 265 mm.
Skull area - 5547 mm2.
Fruit size:
Fetal growth - 44.5 cm.
Thigh length - 66 mm.
The chest in diameter is 88 mm.
PHOTO: 34 weeks of pregnancy: the size of the fetus by ultrasound
35 weeks.
The length of the fetus from the crown to the sacrum is 45 cm. Weight is 2200 g.
Baby head size:
BPR - 88 mm.
The perimeter of the skull is 270 mm.
Skull area - 5810 mm2.
Fruit size:
Fetal growth - 45.5 cm.
Thigh length - 67 mm.
The chest in diameter is 91 mm.
36 weeks.
The length of the fetus from the crown to the sacrum is 46 cm. Weight is 2300 g.
Baby head size:
BPR - 90 mm.
The perimeter of the skull is 272 mm.
Skull area - 6075 mm2.
Fruit size:
Fetal growth - 46.5 cm.
Thigh length - 69 mm.
The chest in diameter is 94 mm.
37 weeks.
The length of the fetus from the crown to the sacrum is 48 cm. Weight is 2800 g.
Baby head size:
BPR - 91 mm.
The perimeter of the skull is 276 mm.
Skull area - 6348 mm2.
Fruit size:
Fetal growth - 48 cm.
Thigh length - 71 mm.
The chest in diameter is 97 mm.
38 weeks.
The length of the fetus from the crown to the sacrum is 50 cm. Weight is 2900 g.
Baby head size:
BPR - 92 mm.
The perimeter of the skull is 282 mm.
Skull area - 6620 mm2.
Fruit size:
Fetal growth - 48 cm.
Thigh length - 71 mm.
The chest in diameter is 98 mm.
39 weeks.
The length of the fetus from the crown to the sacrum is 50 cm. Weight is 3000 g.
Baby head size:
BPR - 94 mm.
The perimeter of the skull is 285 mm.
Skull area - 6680 mm2.
Fruit size:
Fetal growth - 49 cm.
Thigh length - 73 mm.
The chest in diameter is 99 mm.
40 weeks.
The length of the fetus from the crown to the sacrum is 51 cm.
Weight - 3000 g.
Baby head size:
BPR - 95 mm.
The perimeter of the skull is 290 mm.
Skull area - 6770 mm2.
Fruit size:
Fetal growth - 50 cm.
Thigh length - 75 mm.
The chest is 100 mm in diameter.
Do not forget about the error in the average values, as well as the correctly set gestational age, which can lead to an error in calculating the size of the fetus. With multiple pregnancy, other parameters and some lag in size have values.
Material prepared specifically for the site
Immediately after the joyful news of an interesting situation, a woman begins to worry and take care of the developing baby. Doctors come to her aid - at the end of the first month of bearing a child, an ultrasound can already see a fetal egg. Changing its size by weeks allows you to draw conclusions about whether the pregnancy is proceeding correctly.
Fertilized egg: what is it and why follow it?
A fertilized egg is a fertilized egg surrounded by membranes. It is constantly dividing - first into 2 parts, then into 4, etc. As a result of this process, the size of the embryo is constantly increasing. Before fixation in the uterus, which occurs 7 days after conception, the fetal egg receives the necessary substances from the yolk sac. The term "gestational sac" is replaced by "fetus" at the end of 12-14 weeks of pregnancy.
Tracking the size of the fetal egg by weeks is not a whim and not a reinsurance of scrupulous doctors and their patients. This information helps:
- determine the duration of pregnancy;
- name the expected date of birth;
- make sure that the growth of the embryo is normal;
- detect the appearance of pathologies;
- prevent involuntary termination of pregnancy, that is, miscarriage.
Do not put off an ultrasound examination until later. After all, the woman herself, who is preparing for imminent motherhood, is interested in obtaining the above information, first of all.
What numbers create a "portrait" of a tiny embryo?
Medical science has long known the norms of various indicators of the development of the fetal egg in the first 3 months of expecting a child. Examining the embryo, visualized on the monitor, the doctor will first of all pay attention to its shape - at the minimum time it resembles a circle. Next, you need to measure the inner diameter of the fetal egg and tell the woman how long the long-awaited "resident" is inside her. But this diameter is not the same for everyone, as it depends on the individual characteristics of the organism. Therefore, if, when establishing the time elapsed after conception, rely only on this indicator, an error of 1.5 weeks is possible.
Thanks to modern transvaginal ultrasound devices, it is possible to detect a fetal egg measuring 2-4 mm. What period confirms this measurement? No more than 2-3 weeks after the onset of development and 5-6 weeks from the day of the last menstruation.
Read also:
How will this figure change in the future? We offer a small "cheat sheet", which indicates the period of development, and in brackets - the period since the last menstruation:
- 5 (8) weeks - 6 mm;
- 6 (9) weeks - 11-18 mm;
- 7 (10) weeks - 19-26 mm;
- 8 (11) weeks - 27-34 mm;
- 9 (12) weeks - 35-43 mm;
- 10 (13) weeks - 50 mm.
But what women hear during an ultrasound is not always found in the standard list of sizes. Therefore, expectant mothers often have questions - for example, if the fetal egg is 5 mm, what is the gestational age? It's about 5 weeks. And what is the period if the fetal egg is not 5 mm, but 8 mm? Then pregnancy 5 weeks and a few days. During the day, the egg cell surrounded by a membrane will grow by an average of 1 mm, and after crossing the line at 15 weeks, the fetus increases daily by 2-2.5 mm.
To make sure that everything is fine with the future baby, in addition to these data, the area and volume of the fetal egg, as well as the diameter of the yolk sac, are measured. The norm of these indicators for weeks is different.
No less important information is KTR and BPR. How to decipher these abbreviations?
The coccyx-parietal size (KTR) is the length of the embryo from its top to the coccyx. Such measurements make it possible to determine the time of pregnancy as accurately as possible, because the indicator is almost identical in all patients.
The biparietal size of the fetal head (BDP) is the area from the surface of the upper border on the outside to the surface of the lower border on the inside between the parietal bones. BDP is measured starting at 6 weeks after conception.
To understand how the results of ultrasound correspond to the norm, the following table will help.
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Weeks since last menstrual bleeding |
weeks after conception |
Yolk sac diameter |
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When is women's excitement justified?
A woman who has recently learned about her new position does not always hear good news on ultrasound. What can overshadow her hope for a prosperous motherhood?
wrong shape
Before the onset of 5-6 weeks of pregnancy, the doctor sees the fetal egg in the form of a rounded figure. But when the baby's gestation period approaches 2 months, with a longitudinal scan, the embryo will look oval, although it will remain rounded with a transverse one. Other deviations from the normal form are also possible. This pathology most often develops in the presence of neoplasms in the uterus or partial detachment of the placenta.
Placement violations
The fertilized egg must be fixed in the bottom of the uterus or on its back wall, less often in the internal pharynx or in the upper part of the organ. If the embryo is located differently, the doctor assesses how dangerous it is and decides on future fate crumbs.
size pathologies
If the egg in the shell is smaller or larger than the above values, this indicates possible developmental disorders. But since these indicators can fluctuate during the normal course of pregnancy, only a specialist concludes how significant the deviations are.
False fertilized egg
In the case of an ectopic pregnancy, the doctor can still see a fetal egg in the uterine cavity. But in fact, this formation consists of an accumulation of mucus and the secretion of the glands of the fallopian tubes. You can recognize the “deception of the body”: from a normal fertilized egg, this egg will differ in wall thickness and shape.
Empty fertilized egg
At 1-2 weeks, the fetus is not yet noticeable, so it will not work to understand whether it is developing. But an empty egg for more later dates- a warning sign. Most likely, a medical termination of pregnancy will be required. Among the reasons for such a sad situation are the woman's age, genetic disorders, medications that are contraindicated for pregnant women.
