When a woman realizes that she is pregnant, she has new experiences and questions. First, the representative of the weaker sex worries whether the pregnancy will continue, whether there will be a threat of its termination. After some time, the expectant mother is in anticipation of the first ultrasound examination and so on. In this article, we will talk about how you can determine the size of the fetal egg by week. You will find out what diameter this formation has in a given period.
Pregnancy
To begin with, it is worth talking about how conception occurs. A healthy woman ovulates every month. At this moment, the egg leaves the place of its maturation and enters the abdominal cavity. Moving through the fallopian tubes, the gamete meets with the spermatozoon, and fertilization occurs. It is worth noting that this requires unprotected sexual contact between a man and a woman.
After that, the future fetal egg begins to continuously divide and move into the uterus. It is here that the embryo will develop, which will subsequently become a completely independent viable human organism.
How to determine the size of the fetal egg?
Weekly pregnancy was always calculated. Even in ancient times, when there was no modern technology and equipment, doctors considered not months, but periods of seven days. There are several ways to determine the size of the fetal egg by week. Consider them:
Manual inspection. This method has a large error. During the examination, the doctor inserts two fingers into the vagina, and with the other hand probes the uterus through the abdominal cavity. By setting the approximate size of the reproductive organ, the physician determines the size of the fetal egg by week. It is worth noting that during palpation, the doctor does not take into account the number of embryos in the uterus. That is why there is a rather high probability of inaccuracy of this method. The established period may differ from the actual one by about 14 days.
Ultrasound examination. This method, which allows you to determine the size of the fetal egg by week, is more accurate. However, in this case, the error can be about seven days. It should be noted that a lot depends on the attentiveness and professionalism of the doctor, as well as on his equipment. Modern sensors allow you to set the period not only in weeks, but also in days.
Early pregnancy
Some representatives of the weaker sex, as soon as they receive a positive pregnancy test result, are sent for an ultrasound examination. What is the size of the fetal egg during this period? 4 weeks are characterized by the following data. The doctor on the monitor screen may not see education at all. What can we say about the embryo! With good equipment, a physician can see a point, the diameter of which usually does not exceed 2-4 millimeters. However, the specialist will already say with confidence that this is pregnancy.
Fetal development period 5 weeks
What should be the size of the fetal egg in this case? 5 weeks are characterized by an average internal diameter of 6 to 10 millimeters. At the same time, good equipment and a competent specialist can determine the exact number of days. So, what is the size of the fertilized egg by weeks and days?
- 6 or 7 millimeters correspond to a period of 5 weeks and 3 days;
- 8 millimeters corresponds to a period of 5 weeks and 4 days;
- 9 millimeters corresponds to a period of 5 weeks and 5 days;
- 10 millimeters corresponds to a period of 5 weeks and 6 days.
Term six weeks
What is the size of the ovum at this stage? 6 weeks of pregnancy are characterized by an average internal diameter of education from 11 to 18 millimeters. In this case, most often the embryo is already determined, it is possible to measure its coccygeal-temech size. This indicator allows you to more clearly determine the age of the fetus. Based only on the values of the average inner diameter, this pattern can be derived (all measurements are in millimeters):
- 11 corresponds to exactly 6 weeks;
- 12 corresponds to 6 weeks and 1 day;
- 13 corresponds to 6 weeks and 2 days;
- 14 corresponds to 6 weeks and 3 days;
- 15 corresponds to 6 weeks and 4 days;
- 16 and 17 correspond to 6 weeks and 5 days;
- 18 corresponds to 6 weeks and 6 days.
Embryo size at seven weeks
What is the inner diameter of the fetal egg at this time? The data suggests that the average value can range from 19 to 26 millimeters. At the same time, the embryo and the yolk sac present in the egg cavity are already clearly visible. These indicators indicate that the pregnancy is progressing. So, how does the size of the fetal egg change at a given time?
- 19 mm is obtained at exactly 7 weeks;
- 20 mm - at 7 weeks and 1 day;
- 21 mm - at 7 weeks and 2 days;
- 22 mm - at 7 weeks and 3 days;
- 23 mm - at 7 weeks and 4 days;
- 24 or 25 mm - at 7 weeks and 5 days;
- 26 mm - at 7 weeks and 6 days.
Pregnancy 8 weeks: the size of the fetal egg
At this stage, the doctor, during an examination with an ultrasound sensor, can detect indicators ranging from 27 to 34 millimeters. However, you should not rely only on the values \u200b\u200bthat the average inner diameter has when setting the term. At this time, the embryo helps to more accurately determine the age of pregnancy, or rather, its length from the crown to the coccyx. So, if you focus only on the fetal egg, the sizes by weeks and days will be as follows:
- 27 millimeters is exactly eight weeks;
- 28 millimeters is 1 day and 8 weeks;
- 29 millimeters is 2 days and 8 weeks;
- 30 or 31 millimeters is 3 days and 8 weeks;
- 32 millimeters is 4 days and 8 weeks;
- 33 millimeters is 5 days and 8 weeks;
- 34 millimeters is 6 days and 8 weeks.
nine weeks
This time period is characterized by the size of the fetal egg from 35 to 43 millimeters. At the same time, it is already possible to detect the heartbeat of the embryo, which also to some extent allows you to more accurately determine the gestational age.
- 35 mm correspond to 9 weeks exactly;
- 36 or 37 mm - 9 weeks + 1 day;
- 38 mm - 9 weeks + 2 days;
- 39 mm - 9 weeks + 3 days;
- 40 or 41 mm - 9 weeks + 4 days;
- 42 mm - 9 weeks + 5 days;
- 43 mm - 9 weeks + 6 days.
Embryo age - ten weeks
At this stage of development, the fetal egg is in the range from 44 to 50 millimeters. The most accurate values will be as follows:
- 44 millimeters is exactly 10 weeks;
- 45 or 46 millimeters is 10 weeks and 1 day;
- 47 millimeters is 10 weeks and 2 days;
- 48 or 49 millimeters is 10 weeks and 3 days;
- 50 millimeters is 10 weeks and 4 days.
Further measurement of the average internal diameter is already pointless. During the examination, specialists often use the coccygeal-temechkovy measurement and other data. For example, approximate weight, height from crown to heels, volume of the head, abdomen and chest. The fetus at this time is already moving and showing all signs of life.
Summing up and conclusion
Now you know what the average size is the diameter of the ovum at a given time. Remember that sometimes there are errors, and the doctor cannot accurately determine the period. Also, in some cases, there are malfunctions in the equipment. If the specialist did not find an embryo in the cavity of the fetal egg, then you will be assigned additional diagnostics in two to four weeks. Also, sometimes a blood test is prescribed to confirm the fact of a developing pregnancy. The laboratory assistant determines the amount of chorionic gonadotropin in the body and sets the approximate gestational age. A fertilized egg is most often seen on ultrasound only when the hCG value is more than 1000 IU.
Stay healthy and have an easy pregnancy!
1st week
Your baby is still in the plans
Your last period has just started and you are already planning a pregnancy.
2nd week
moment of conception
Pregnancy occurs on the 14th day. As a result of ejaculation, millions of spermatozoa move through the vagina through the fallopian tube. Only one sperm can get to the egg. This is the moment of conception.
3rd week
Fruit size:
A blastocyst is formed - a hollow, fluid-filled germinal vesicle, a cluster of cells: it is still barely visible to the naked eye and its size is about 0.1-0.2 mm in diameter.
4th week
Fruit size:
In one week, the baby almost doubles in size: its length does not exceed half a millimeter.
5th week
Fruit size:
Over the past week, the baby has doubled in size: now its length is 1.5 mm.
Inner diameter (mm) – 18
Area (mm2) – 245
Volume (mm3) – 2187
The average size of the embryo
Coccyx-parietal size (mm) – 3
6th week
Fruit size:
The length of the baby now reaches 4 mm.
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 22
Area (mm2) - 363
Volume (mm3) – 3993
The average size of the embryo
Coccyx-parietal size (mm) – 6
– 3
7th week
fruit weight:
Fruit size:
The length of the baby now reaches 1.5 cm, and at this stage almost half of it falls on a disproportionately large head.
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 24
Area (mm2) – 432
Volume (mm3) – 6912
The average size of the embryo
Coccyx-parietal size (mm) – 10
Yolk sac diameter (mm3) – 4
8th week
fruit weight:
The length from the crown to the sacrum is approximately 8-11 mm.
Weight - about 1.5 g.
Fruit size:
Its length from crown to tailbone is 2.2 cm and is called, respectively, the parietal-coccygeal length. This expression applies even after the legs have grown to full length - since they are often bent, this makes it difficult to take measurements from the crown to the heels.
With what to compare?
Now, in size and shape, the baby resembles a cashew nut.
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 30
Area (mm2) – 675
Volume (mm3) – 13490
The average size of the embryo
Coccyx-parietal size (mm) – 16
Biparietal size (mm) – 6
Yolk sac diameter (mm3) – 4,5
9th week
fruit weight:
Weight - about 2 g.
Fruit size:
The length from the crown to the sacrum is approximately 13-17 mm.
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 33
Area (mm2) – 972
Volume (mm3) – 16380
The average size of the embryo
Coccyx-parietal size (mm) – 23
Biparietal size (mm) – 8,5
Yolk sac diameter (mm3) – 5
10th week
fruit weight:
Weight - about 4 g.
Fruit size:
The length from the crown to the sacrum is approximately 27-35 mm.
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 39
Area (mm2) – 1210
Volume (mm3) – 31870
The average size of the embryo
Coccyx-parietal size (mm) – 31
Biparietal size (mm) – 11
Yolk sac diameter (mm3) – 5,1
11th week
fruit weight:
The length from the crown to the sacrum is approximately 55 mm.
Weight - about 7 g.
Fruit size:
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 47
Area (mm2) – 1728
Volume (mm3) – 55290
The average size of the embryo
Coccyx-parietal size (mm) – 41
Biparietal size (mm) – 15
Yolk sac diameter (mm3) – 5,5
Height and weight by ultrasound
Height (cm) - 6,8
Weight (g) - 11
Thigh length (mm) – 7
chest diameter(mm)– 20
12th week
fruit weight:
The length from the crown to the sacrum is approximately 70-90 mm.
Weight - about 14-15 g.
Fruit size:
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 56
Area (mm2) – 2350
Volume (mm3) – 87808
The average size of the embryo
Coccyx-parietal size (mm) – 53
Biparietal size (mm) – 20
Yolk sac diameter (mm3) – 6
Height and weight by ultrasound
Height (cm) - 8,2
Weight (g) - 19
Thigh length (mm) – 9
chest diameter(mm)– 24
13th week
fruit weight:
The length from the crown to the sacrum is 10.5 cm.
Weight - approximately 28.3 g.
Fruit size:
The average size of the ovum in the first trimester of pregnancy
Inner diameter (mm) – 65
Area (mm2) – 3072
Volume (mm3) – 131070
The average size of the embryo
Coccyx-parietal size (mm) – 66
Biparietal size (mm) – 24
Yolk sac diameter (mm3) – 5,8
Height and weight by ultrasound
Height (cm) - 10
Weight (g) - 31
Thigh length (mm) - 12
chest diameter(mm)– 24
14th week
fruit weight:
Length from crown to sacrum -12.5 - 13 cm.
Weight - about 90-100 g.
Fruit size:
Biparietal size (mm) – 26
Skull perimeter (mm) – 80
Skull area (mm2) – 510
Height and weight by ultrasound
Height (cm) - 12,3
Weight (g) - 52
Thigh length (mm) - 16
chest diameter(mm)– 26
15th week
fruit weight:
The length from the crown to the sacrum is 93-103 mm.
Weight - about 70 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 32
Skull perimeter (mm) – 90
Skull area (mm2) – 675
Height and weight by ultrasound
Height (cm) - 14,2
Weight (g) - 77
Thigh length (mm) - 19
chest diameter(mm)– 28
16th week
fruit weight:
length: 16 cm;
weight: 85 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 35
Skull perimeter (mm) – 102
Skull area (mm2) – 860
Height and weight by ultrasound
Height (cm) - 16,4
Weight (g) - 118
Thigh length (mm) - 22
chest diameter(mm)– 34
17th week
fruit weight:
The length from the crown to the sacrum is 15-17 cm.
Weight - about 142 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 39
Skull perimeter (mm) – 120
Skull area (mm2) – 1080
Height and weight by ultrasound
Height (cm) - 18
Weight (g) - 160
Thigh length (mm) - 24
chest diameter(mm)– 38
18th week
fruit weight:
The length from the crown to the sacrum is 20.5 cm.
Weight - about 198-200 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 42
Skull perimeter (mm) – 126
Skull area (mm2) – 1320
Height and weight by ultrasound
Height (cm) - 20,3
Weight (g) - 217
Thigh length (mm) - 28
Chest diameter (mm)– 41
19th week
fruit weight:
The length from the crown to the sacrum is 20-22 cm.
Weight - about 227-230 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 44
Skull perimeter (mm) – 138
Skull area (mm2) – 1450
Height and weight by ultrasound
Height (cm) - 22,1
Weight (g) - 270
Thigh length (mm) - 31
chest diameter(mm)– 44
20th week
fruit weight:
Weight - about 283-285 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 47
Skull perimeter (mm) – 144
Skull area (mm2) – 1730
Height and weight by ultrasound
Height (cm) - 24,1
Weight (g) - 345
Thigh length (mm) - 34
chest diameter(mm)– 48
21st week
fruit weight:
The length from the crown to the sacrum is about 25 cm.
Weight - about 360-370 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 51
Skull perimeter (mm) – 151
Skull area (mm2) – 1875
Height and weight by ultrasound
Height (cm) - 25,9
Weight (g) - 416
Thigh length (mm) - 37
chest diameter(mm)– 50
22nd week
fruit weight:
The length from the crown to the sacrum is about 27-27.5 cm.
Weight - about 420-425 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 54
Skull perimeter (mm) – 162
Skull area (mm2) – 2190
Height and weight by ultrasound
Height (cm) - 27,8
Weight (g) - 506
Thigh length (mm) - 40
chest diameter(mm)– 53
23rd week
fruit weight:
The length from the crown to the sacrum is about 30 cm.
Weight - about 500-510 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 58
Skull perimeter (mm) – 173
Skull area (mm2) – 2520
Height and weight by ultrasound
Height (cm) - 29,7
Weight (g) - 607
Thigh length (mm) - 43
chest diameter(mm)– 56
24th week
fruit weight:
The length from the crown to the sacrum is about 29-30 cm.
Weight - about 590 - 595 g
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 61
Skull perimeter (mm) – 183
Skull area (mm2) – 2710
Height and weight by ultrasound
Height (cm) - 31,2
Weight (g) - 733
Thigh length (mm) - 46
Chest diameter (mm)– 59
25th week
fruit weight:
The length from the crown to the sacrum is about 31 cm.
Weight - about 700-709 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 64
Skull perimeter (mm) – 194
Skull area (mm2) – 3072
Height and weight by ultrasound
Height (cm) - 32,4
Weight (g) - 844
Thigh length (mm) - 48
chest diameter(mm)– 62
26th week
fruit weight:
The length from the crown to the sacrum is about 32.5-33 cm.
Weight - about 794 - 800 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 67
Skull perimeter (mm) – 199
Skull area (mm2) – 3260
Height and weight by ultrasound
Height (cm) - 33,9
Weight (g) - 969
Thigh length (mm) - 51
chest diameter(mm)– 64
27th week
fruit weight:
The length from the crown to the sacrum is about 34 cm.
Weight - approximately 900 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 69
Skull perimeter (mm) – 215
Skull area (mm2) – 3675
Height and weight by ultrasound
Height (cm) - 35,5
Weight (g) - 1135
Thigh length (mm) - 53
chest diameter(mm)– 69
28th week
fruit weight:
The length from the crown to the sacrum is about 35 cm.
Weight - approximately 1000 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 72
Skull perimeter (mm) – 218
Skull area (mm2) – 3880
Height and weight by ultrasound
Height (cm) - 37,2
Weight (g) - 1319
Thigh length (mm) - 55
chest diameter(mm)– 73
29th week
fruit weight:
The length from the crown to the sacrum is about 36-37 cm.
Weight - approximately 1150-1160 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 75
Skull perimeter (mm) – 225
Skull area (mm2) – 4107
Height and weight by ultrasound
Height (cm) - 38,6
Weight (g) - 1482
Thigh length (mm) - 57
chest diameter(mm)– 76
30th week
fruit weight:
The length from the crown to the sacrum is about 37.5 cm.
Weight - approximately 1360 - 1400 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 78
Skull perimeter (mm) – 234
Skull area (mm2) – 4563
Height and weight by ultrasound
Height (cm) - 39,9
Weight (g) - 1636
Thigh length (mm) - 59
chest diameter(mm)– 79
31st week
fruit weight:
The length from the crown to the sacrum is about 38-39 cm.
Weight - approximately 1500 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 80
Skull perimeter (mm) – 240
Skull area (mm2) – 4810
Height and weight by ultrasound
Height (cm) - 41,1
Weight (g) - 1779
Thigh length (mm) - 61
chest diameter(mm)– 81
32nd week
fruit weight:
The length from the crown to the sacrum is about 40 cm.
Weight - approximately 1700 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 82
Skull perimeter (mm) – 246
Skull area (mm2) – 5040
Height and weight by ultrasound
Height (cm) - 42,3
Weight (g) - 1930
Thigh length (mm) - 63
chest diameter(mm)– 83
33rd week
fruit weight:
Weight - approximately 1800 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 84
Skull perimeter (mm) – 255
Skull area (mm2) – 5290
Height and weight by ultrasound
Height (cm) - 43,6
Weight (g) - 2088
Thigh length (mm) - 65
chest diameter(mm)– 85
34th week
fruit weight:
The length from the crown to the sacrum is about 42 cm.
Weight - approximately 2000 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 86
Skull perimeter (mm) – 264
Skull area (mm2) – 5547
Height and weight by ultrasound
Height (cm) - 44,5
Weight (g) - 2248
Thigh length (mm) - 66
chest diameter(mm)– 88
35th week
fruit weight:
The length from the crown to the sacrum is about 45 cm.
Weight - approximately 2215 - 2220 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 88
Skull perimeter (mm) – 270
Skull area (mm2) – 5810
Height and weight by ultrasound
Height (cm) - 45,4
Weight (g) - 2414
Thigh length (mm) - 67
chest diameter(mm)– 91
36th week
fruit weight:
The length from the crown to the sacrum is about 45-46 cm.
Weight - approximately 2300 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 90
Skull perimeter (mm) – 272
Skull area (mm2) – 6075
Height and weight by ultrasound
Height (cm) - 46,6
Weight (g) - 2612
Thigh length (mm) - 69
chest diameter(mm)– 94
37th week
fruit weight:
The length from the crown to the sacrum is about 48 cm.
Weight - approximately 2800 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 91
Skull perimeter (mm) – 276
Skull area (mm2) – 6348
Height and weight by ultrasound
Height (cm) - 47,9
Weight (g) - 2820
Thigh length (mm) - 71
chest diameter(mm)– 97
38th week
fruit weight:
Weight - approximately 2900 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 92
Skull perimeter (mm) – 282
Skull area (mm2) – 6620
Height and weight by ultrasound
Height (cm) - 47,9
Weight (g) - 2820
Thigh length (mm) - 71
chest diameter(mm)– 97
39th week
fruit weight:
The length from the crown to the sacrum is about 50 cm.
Weight - approximately 3000 g.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 94
Skull perimeter (mm) – 285
Skull area (mm2) – 6684
Height and weight by ultrasound
Height (cm) - 49
Weight (g) - 2992
Thigh length (mm) - 73
chest diameter(mm)– 99
40th week
fruit weight:
The usual length of a newborn is 48-51 cm, and the average weight is 3000-3100 grams.
Fruit size:
Average size of the fetal head
Biparietal size (mm) – 95
Skull perimeter (mm) – 290
Skull area (mm2) – 6768
Height and weight by ultrasound
Height (cm) - 50,2
Weight (g) - 3170
Thigh length (mm) - 75
chest diameter(mm)– 101
Throughout the nine months, every mother worries about the correct development of the baby. It is precisely to ensure full control over the development of the child in the womb and the timely detection of any abnormalities that pregnant women are strongly recommended to regularly visit the leading doctor in order to find out the size of the fetus by weeks of pregnancy.
Accurate diagnosis involves the use of ultrasound methods. Based on the results obtained, the specialist can determine how proportionally the baby develops, and whether the data obtained regarding growth and development correspond to the established norms.
What indicators are taken into account?
The key parameters that make it possible to determine the characteristics of the development of the fetus are indicators of its height and weight, but they begin to be measured only in the second part of the first trimester. Until that time, the dimensions of the embryo are so small that their measurement is extremely difficult.
According to medical indications, every pregnant woman is required to undergo at least three ultrasound examinations during all nine months. This number of procedures is considered minimal and can be increased by the decision of specialists, if there is a need to obtain additional information about the development of the fetus.
Periodic ultrasound is necessary for the timely detection of serious pathologies and the prevention of complications. As a rule, such studies are carried out no earlier than 10 and no later than 14 weeks, as well as in the second trimester in the period from 18 to 21 weeks.
To facilitate the task in medical practice, it is customary to measure the size of the fetus by weeks, because the fetal egg increases in volume almost daily.
The results of each ultrasound are recorded in protocols, from which information can be obtained regarding the symmetry of the development of the fetus, its growth rate and the compliance of indicators with established and used standards.
Throughout pregnancy, as the fetus develops, various parameters are taken into account. For example, up to 13 weeks, experts focus more on the analysis of the coccygeal-parietal length, measured from the coccyx to the parietal region of the fetus. This feature of the measurement is due to the fact that the fetus is in a bent position, so the opportunity to obtain the first data on growth appears no earlier than 14 weeks.
During the second scheduled ultrasound, specialists focus more on other indicators presented:
- fronto-occipital size or longitudinal line;
- circles of the skull, abdomen and chest;
- length of the lower and upper limbs.
An important factor indicating the normal development of the fetus is not only compliance with established standards, but also the symmetry of the measurements obtained.
Fetal size by week of pregnancy
The onset of pregnancy occurs by the end of the second week of the menstrual cycle, which is considered the moment of conception. The features of this process are known to everyone since school. Male ejaculation is accompanied by the release of millions of spermatozoa, only one of which, after entering the vagina and through the fallopian tubes, will be able to approach the egg.
During the third week, the formation of an embryonic vesicle occurs, inside which there is a liquid and cells in large quantities. This bubble is so small that it is almost impossible to see it without special equipment. To be able to imagine the parameters of the bubble, compare it with a pea, the size of which does not exceed 0.2 mm in diameter.
From the beginning of the fourth week, the active development of the fetus begins, which almost doubles every week. So, by the end of the next week, the length of the fetal egg reaches 0.5 mm. Already at this stage, specialists have the first opportunity to obtain real data on the development of the fetus, which can be presented in the form of a table.
Table 1. Dimensions of the ovum from 1 to 13 weeks
|
Period |
Length indicators, mm |
Inner diameter, mm3 |
Area, mm2 | Volume, mm2 | Coccyx-parietal size, mm |
Yolk sac diameter, mm3 |
| 1 Week | — | — | — | — | — | — |
| 2 weeks | — | — | — | — | — | — |
| 3 week | 0,2 | — | — | — | — | — |
| 4 week | 0,5 | — | — | — | — | — |
| 5 week | 1,5 | 18 | 245 | 2 187 | 3 | — |
| 6 week | 4 | 22 | 363 | 3 993 | 6 | 3 |
| 7 week | 7 | 22 | 432 | 6 912 | 10 | 4 |
| 8 week | 10 | 30 | 675 | 13 490 | 16 | 4,5 |
| 9 week | 15 | 33 | 972 | 16 380 | 23 | 5 |
| 10 week | 31 | 39 | 1 210 | 31 870 | 31 | 5,1 |
| 11 week | 55 | 47 | 1 728 | 55 290 | 41 | 5,5 |
| 12 week | 80 | 56 | 2 350 | 87 808 | 53 | 6 |
| 13 week | 105 | 65 | 3 072 | 131 070 | 66 | 6 |
The lengths given in the table are measured from the crown of the head to the coccyx and are averaged. According to experts, due to the distinctive features of development, slight deviations from the given average indicators are allowed. A significant deviation, as well as a violation of the permissible proportions between the indicators, which is an important factor, is a prerequisite for further research.
By the end of the eighth week, the length of the fetal egg reaches 11 mm. According to numerous studies, the weight of the fetus at this stage does not exceed 1.5 grams. Over the next week, there is an increase in weight by another 0.5 g, and by the end of the tenth week, it can reach 4 g.
At the eleventh, through ultrasound, it becomes possible to obtain the first data on the length of the thigh and chest, which are respectively 7 and 20 mm. By this period, the weight of the fetus reaches 11 g. By the end of 12 weeks, the diameter of the chest will reach 24 mm, and the diameter of the thigh - 9 mm.
From the 11th to the 40th week, specialists carefully examine not only the general indicators of length, but also the parameters of individual parts of the body, which allows you to get a general and complete picture of the correct development of the fetus.
Starting from the thirteenth, during examinations, measurements of the baby’s skull are also taken into account, whose weight by this time reaches 30 g.
Table 2. Sizes of the fetal egg by week: from the 13th to the 40th
| Period | Length indicators, mm | Thigh length, mm | Chest diameter, mm | Skull perimeter, mm | Skull area, mm2 |
| 11 week | 55 | 7 | 20 | — | — |
| 12 week | 80 | 9 | 24 | — | — |
| 13 week | 105 | 12 | 25 | — | — |
| 14 week | 110 | 16 | 26 | 80 | 510 |
| 15 week | 115 | 19 | 28 | 90 | 675 |
| 16 week | 160 | 22 | 34 | 102 | 860 |
| 17 week | 170 | 24 | 38 | 120 | 1 080 |
| 18 week | 205 | 28 | 41 | 126 | 1 320 |
| 19 week | 215 | 31 | 44 | 138 | 1 450 |
| 20 week | 250 | 34 | 48 | 144 | 1 730 |
| 21 weeks | 260 | 37 | 50 | 151 | 1 875 |
| 22 week | 270 | 40 | 53 | 162 | 2 190 |
| 23 week | 385 | 43 | 56 | 173 | 2 520 |
| 24 week | 300 | 46 | 59 | 183 | 2 710 |
| 25 week | 310 | 48 | 62 | 194 | 3 072 |
| 26 week | 325 | 51 | 64 | 199 | 3 260 |
| 27 week | 340 | 53 | 69 | 215 | 3 675 |
| 28 week | 350 | 55 | 73 | 218 | 3 880 |
| 29 week | 365 | 57 | 76 | 225 | 4 170 |
| 30 week | 375 | 59 | 79 | 234 | 4 563 |
| 31 weeks | 385 | 61 | 81 | 240 | 4 810 |
| 32 week | 400 | 63 | 83 | 246 | 5 040 |
| 33 week | 410 | 65 | 85 | 255 | 5 290 |
| 34 week | 420 | 66 | 88 | 264 | 5 547 |
| 35 week | 450 | 67 | 91 | 270 | 5 810 |
| 36 week | 455 | 69 | 94 | 272 | 6 075 |
| 37 week | 480 | 71 | 97 | 276 | 6 348 |
| 38 week | 485 | 71 | 97 | 282 | 6 620 |
| 39 week | 490 | 73 | 99 | 285 | 6 684 |
| 40 week | 500 | 75 | 101 | 290 | 6 768 |
Biparental fetal size by week
Another important indicator that experts take into account in their studies is the biparietal size, represented by the distance between the outer surface of the upper contour and the inner region of the lower contour between the parietal bones.
As in the case of other indicators, minor deviations from the norm are allowed when analyzing the obtained biparietal size. If the established data are exceeded, the specialist must also evaluate other parameters, represented by the circumference of the abdomen, the length of the limbs.
The analysis of this indicator is extremely important, because its deviations from the norm in many cases may indicate serious pathologies, represented by hernias, tumors and other volumetric formations, in which the only way out may be termination of pregnancy. The insufficient development of the baby's head or a decrease in its size is also considered undesirable, which may be due to underdevelopment or lack of anatomical structures of the brain. In this case, experts also strongly recommend termination of pregnancy.
Often in the third trimester, reduced indicators of BDP are diagnosed, which, if detected in a timely manner, can be successfully corrected.
As a rule, in this case, a diagnosis of intrauterine growth retardation is made, and the pregnant woman is prescribed treatment with drugs that improve uteroplacental blood flow and ensure the transport of essential nutrients.
In medical practice, the following average indicators of the biparietal size of the fetus are used:
- 8 week - 6 mm;
- 9 week - 8.5;
- 10 week - 11 mm;
- 11 weeks - 15 mm;
- 12 weeks - 20 mm;
- 13 week - 24 mm;
- 14 weeks - 26 mm;
- 15 week - 32 mm;
- 16 weeks - 35 mm;
- 17 week - 39 mm;
- 18 weeks - 42 mm;
- 19 week - 44 mm;
- 20 week - 47 mm;
- 21 weeks - 51 mm;
- 22 weeks - 54 mm;
- 23 weeks - 58 mm;
- 24 weeks - 61 mm;
- 25 week - 64 mm;
- 26 weeks - 67 mm;
- 27 week - 69 mm;
- 28 weeks - 72 mm;
- 29 week - 75 mm;
- 30 week - 78 mm;
- 31 weeks - 80 mm;
- 32 weeks - 82 mm;
- 33 weeks - 84 mm;
- 34 weeks - 86 mm;
- 35 week - 88 mm;
- 36 week - 90 mm;
- 37 week - 91 mm;
- 38 weeks - 92 mm;
- 39 week - 94 mm;
- 40 weeks - 95 mm.
Of course, it is not possible to determine the exact weight of the fetus by means of an ultrasound examination, so experts are guided by other sizes and established norms. For the first time, the weight of the fetus is indicated on the eighth week, from which it becomes possible to obtain the first necessary data.
Table 3. Fetal weight by week
| Period | |
| 8 week | 1 |
| 9 week | 2 |
| 10 week | 4 |
| 11 week | 7 |
| 12 week | 14 |
| 13 week | 23 |
| 14 week | 43 |
| 15 week | 70 |
| 16 week | 100 |
| 17 week | 140 |
| 18 week | 190 |
| 19 week | 240 |
| 20 week | 300 |
| 21 weeks | 360 |
| 22 week | 430 |
| 23 week | 501 |
| 24 week | 600 |
| 25 week | 660 |
| 26 week | 760 |
| 27 week | 875 |
| 28 week | 1005 |
| 29 week | 1153 |
| 30 week | 1319 |
| 31 weeks | 1502 |
| 32 week | 1702 |
| 33 week | 1918 |
| 34 week | 2146 |
| 35 week | 2383 |
| 36 week | 2622 |
| 37 week | 2859 |
| 38 week | 3083 |
| 39 week | 3288 |
| 40 week | 3462 |
As a rule, from the data obtained after an ultrasound examination, it is not easy for many women to understand how large the fetus is at this stage. To facilitate this task, the size of the fetal egg by week can be compared with well-known objects. As already noted, the first indicators of the length of the fetus can be obtained only in the third week, when its diameter is 0.2 mm. It is extremely difficult to examine the fetus at this time, and it can only be compared with a poppy seed.
By the end of the fourth week, the fruit almost doubles in size and now it can be safely compared with sesame seeds in size. By the end of the fifth, the fetal egg acquires dimensions comparable to sunflower seeds.
Do you know which bird is considered the smallest on the planet? These are hummingbirds, whose sizes rarely exceed 5.7 centimeters, and their weight is in the range from 1.6 to 2 g. It is with the egg of this bird that a human fetus can be compared in size in the sixth week of its development. By the end of the seventh, its size is comparable to the parameters of an ordinary bean.
On the eighth fruit, in terms of parameters, it can be compared with an unripe olive, and by the end of the ninth - with a large grape.
At the tenth week, the fetus reaches the size of a candy, which doctors do not recommend for pregnant women to lean on. The fruit reaches the size of an apricot by the end of the next period used as a unit of measurement. At the 12th week, the fruit can be compared with a pea pod, and by the end of the thirteenth - with a ripe fig.
Over the next 7 days, the fruit will grow to the size of a medium pear, and after another week - to the size of an avocado. The average weight of newborn kittens is about 100 g. This is how much a human fetus weighs at the 16th week of its development, and in length it can be compared with an average carrot.
At week 17, the fetus can be compared with a medium potato, and at the end of the eighteenth, with a large tomato.
Imagine a big banana in your hands. It is these sizes that the baby reaches by the end of the nineteenth period. At the 20th week, it can be compared to a small hare. Have you seen such an exotic fruit as Thai mango? At 21 weeks, the weight of the fetus can be compared with it.
Among the penguins, the largest and heaviest are representatives of the Imperial species, whose height often reaches 125 cm, and their weight is 50 kg. Eggs of emperor penguins weigh up to 450 g. This is how much a human fetus weighs at 22 weeks of its development.
At week 23, it can be compared in terms of length to a corncob, and by the end of week 24, it can be compared to the weight of a green coconut. By the end of the next period, the size of the baby in the womb can be compared with newborn polar bear cubs, which, despite the impressive volume of adults, are born quite small.
By the end of the 26th week, the baby's weight can be compared with an average head of broccoli, and by the 27th - with a pomelo fruit.
If we take for comparison the length of the baby from the heels to the crown, then at 28 weeks it is comparable to the growth of a newborn tiger cub. The largest bird on the planet is the African ostrich, which can grow up to 200 centimeters and weigh 120 kg. The eggs of these birds weigh an average of 1,200 g. It is this weight that is considered the norm for a baby at the 29th week of its development.
By the end of the next period, the child is comparable to the weight of a six-month-old kitten, and by the end of 31 weeks - to the weight of a newborn lion cub.
In terms of growth, a baby at 32 weeks can be compared with a small blue penguin, and by the end of the next period, it reaches the weight of an average pineapple. At week 34, the baby acquires the size of a ripe melon of medium parameters.
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Conception occurs by the fusion of a male sperm with a female egg. As a result of such a connection, an embryo is formed, a group of cells in the shell, which, as they move towards the uterus, begin to divide. After 7 days, it is attached to the uterus, its growth and development begins. The size of the fetal egg by week of pregnancy is determined using ultrasound, 7-10 days after the delay of the monthly cycle.
Formation and emergence of the fetus
The formation of an embryo is based on active division at the cellular level. The cells of the embryo grow, due to which the sizes increase. The process continues for 6-7 days, as it moves through the fallopian tube to the uterine cavity, where implantation will occur.Initially, nutrition occurs through independent resources. Once attached, nutrients enter through the uterus, and at the same time, the placenta begins to form to further protect and breathe the baby.
At 4-5 weeks, with the help of ultrasound, you can see a rounded shape, which reaches about 4 mm in diameter. And only at the beginning of the second month of intrauterine development, on the ultrasound monitor, the formed baby becomes noticeable.
Due to various anomalies, the absence of an embryo can be diagnosed when the embryo, for various reasons, has not formed. After a certain period of time, a second study is scheduled to confirm the diagnosis by heartbeat, which occurs in the middle of the second month.
The fetometric indicator of SVD estimates the diameter and may vary, when determining the gestation period within 10 days. Therefore, in order to determine the term, additional parameters must be taken into account.
The size of the fetal egg by week of pregnancy: table
The size of the ovum at the 5th week of gestation is about 5-6 mm. As the shell grows and develops, the cells continue to actively divide. Already from the 12th week of gestation, the embryo is considered a full-fledged fetus, a child.The gestational age by the size of the shell is determined in accordance with the diameter, area, volume, and is also measured:
- KTP - coccygeal-parietal measurement;
- Biparietal;
- Yolk sac diameter.
| Period by last menstrual period (weeks) | Conception time (weeks) | KTP (coccygeal-parietal size) mm | BR (Bipareital size) mm. | Yolk sac diameter (mm3) |
|---|---|---|---|---|
| Table 1 - The gestational age for the fetal egg | ||||
| 5 | 3 | 18 | 245 | 2187 |
| 6 | 4 | 22 | 363 | 3993 |
| 7 | 5 | 24 | 432 | 6912 |
| 8 | 6 | 30 | 675 | 13490 |
| 9 | 7 | 33 | 972 | 16380 |
| 10 | 8 | 39 | 1210 | 31870 |
| 11 | 9 | 47 | 1728 | 55290 |
| 12 | 10 | 56 | 2350 | 87808 |
| 13 | 11 | 65 | 3072 | 131070 |
| Table 2 - Measurements depending on the period of intrauterine development | ||||
| 5 | 3 | 3 | - | - |
| 6 | 4 | 6 | - | 3 |
| 7 | 5 | 10 | - | 4 |
| 8 | 6 | 16 | 6,0 | 4,5 |
| 9 | 7 | 23 | 8,5 | 5,0 |
| 1 | 8 | 31 | 11,0 | 5,1 |
| 11 | 9 | 41 | 15,0 | 5,5 |
| 12 | 10 | 53 | 20,0 | 6,0 |
| 13 | 11 | 66 | 24,0 | 5,8 |
With a detailed study of the table, it becomes clear that development occurs quite quickly, and assessment is assigned only in the first trimester. After this period, the parameters of the fetus itself will be studied, in which the limbs, head and internal organs will be formed.
Does a fertilized egg grow during a frozen pregnancy?
The shell of the fetus during a missed pregnancy can grow and increase if the formation of an embryo does not occur during cell division, i.e. an empty fetal egg is diagnosed. The pathology is characterized by all the signs of the onset of gestation, hCG is produced and the placenta is formed.This situation is anomalous and occurs quite rarely. It is necessary to determine the absence of an embryo in a timely manner and monitor the growth dynamics so that the body itself stops the formation through a miscarriage. In rare cases, the intervention of specialists for a planned interruption may be required to avoid complications.
The main reasons for stopping development are:
- chronic infectious diseases;
- hereditary factor;
- drug intoxication;
- unfavorable environment;
- bad habits - smoking and alcohol abuse.
Only doctors and medical specialists are able to assess the condition of the fetus. It is not necessary to independently determine deviations from the standards, perhaps such a formation will be considered within the normal state.
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