For infertile people, choosing to do IVF is a shortcut.
But unlike natural conception, many pregnant mothers who have done IVF are always confused about how to calculate the IVF pregnancy cycle.
In order to let expectant mothers know what to expect, let's talk about the things that calculate the expected date and gestational age after IVF pregnancy
Under normal circumstances, after a woman becomes pregnant, the doctor will calculate the expected date of delivery of the fetus, determine the approximate time of delivery, and the age of the fetus in the womb is calculated in weeks, and the fetus can be judged to be mature or not according to the gestational age.
Medically, the expected date of delivery is calculated from the first day of the last menstrual period, and the entire gestation period is 280 days and 10 gestational months (each pregnancy month is 28 days or 4 weeks), which is what we usually call "October pregnancy".
Calculation of the expected date of natural pregnancy
Natural pregnancy is mainly calculated based on the time of the last menstrual period.
The month of the last menstrual period is increased by 9 or minus 3 (3 at 4 o'clock in the month of ≥; 9 at 3 o'clock in the ≤) is the number of months of the expected date of delivery; the number of days plus 7 is the number of days of the expected date of delivery.
For example:
The last menstrual period is February 1, 2019, the month is 2 +9, the date is 1 +7, and the due date = November 8, 2019.
Another example: the last menstrual period is June 15, 2019, the month is 6-3, the date is 15 + 7, and the expected date of delivery = March 22, 2020.
But for women who have successfully conceived by IVF, the date of the "last menstrual period" is not the same as the actual date of the last menstrual period due to the use of ovulation-stimulating drugs during treatment.
Therefore, for IVF mothers, after pregnancy, we calculate it in the following ways:
1. Depending on the date of transfer and the type of embryo transferred
Whether it is a fresh embryo transfer or a freeze-thaw embryo transfer, the method of estimating the last menstrual period is the same. The estimated date of delivery is calculated by pushing forward 14 + 3 = 17 days (fissile embryos) or forward 14 + 5 = 19 days (blastocysts) as the first day of the last menstrual period.
For example, on May 30, if the embryo is transferred, the last menstrual period is May 13 if the embryo is transferred, and if the blastocyst is transferred, the last menstrual period is May 11.
2. Measurement of gestational sac diameter (GSD) during early pregnancy
When the yolk sac and embryos cannot yet be displayed, gestational age can be estimated by measuring the size of the gestational sac. The commonly used calculation method is: the number of days of pregnancy (d) = 30 days + GSD (mm) of gestational sac diameter.
For example, when ultrasound measures the average diameter of a gestational sac of 5 mm, the gestational age is 35 days according to the formula. This method is suitable for 7 weeks of pregnancy, due to the irregular shape of the gestational sac and the influence of bladder filling, the measured value varies greatly, so it is for reference only.
3. Head and hip length (CRL) during early pregnancy
Measuring CRL during 6-12 weeks' gestation is the most accurate way to estimate gestational age. The measurement was not accurate at the beginning of 6 weeks because the embryo was too small, but the linear germ could be accurately measured after a few days. Since the normal embryonic growth rate is almost linear at a rate of 1 mm/d, the size of the gestational age is approximately equal to the length (mm) of the embryo plus 42 days.
namely:
Gestational age (d) = embryo length (mm) + 42.
The following formula can also be used to calculate gestational age:
Gestational age (weeks) = CRL (cm) + 6.5.
Note: This calculation method is suitable for 7-12 weeks of pregnancy.
For example, ultrasonic measurement crll4.5cm, gestational week = 4.5 + 6.5 = 11 weeks, in addition, there is no obvious difference between the statistical crl calculation and singleton pregnancy in twin pregnancy, and there is no obvious difference between single and double chorionic capillary, it should be noted that the CRL is better in 4-60mm when twins are consistent.
The expected date of delivery for IVF is calculated as such
1. Calculated according to the transplant day
The ovulation period is 14 days forward on the first day of the next menstrual period, and the egg retrieval day is equivalent to the ovulation day for pregnant women who are newly transferred during the IVF egg retrieval cycle, so it is estimated that the first day of the last menstrual period should be 14 days before the egg retrieval date.
Regardless of the ovulation induction regimen adopted in the IVF cycle, the egg retrieval date can be pushed forward 14 days as the first day of the last menstrual period, with a month of +9, or -3, and a date of +7.
Another method of calculating the due date is to calculate the number of days of embryo transfer, so that either the fresh cycle of egg retrieval, or the frozen embryo transfer cycle, regardless of the ovarian stimulation regimen, can be used.
In natural pregnancy, the 14th day of menstruation is the day of ovulation, and the egg is generally fertilized within 12 to 24 hours after the egg is released, and it develops into an 8-cell cleft embryo in about 3 days, and a blastocyst at 5 days.
Ivycles in vitro fertilization after IVF 8-cell embryo transfer or blastocyst stage transfer, equivalent to ovulation period days + 3 or + 5 days, so the transfer date before the 14 + 3 = 17 days (8-cell stage transfer) or forward 14 + 5 = 19 days (blastocyst transfer) as the first day of the last menstrual period, according to this estimated due date.
Ivy reduction of fertility for the last menstrual period is more in line with the medical calculation criteria for the expected date of delivery, and is generally more accurate.
2. B-ultrasound calculation according to early pregnancy
Ultrasound examination in the early post-conception period, such as ultrasound examination at 45 days of pregnancy, B ultrasound examination at 70 days of pregnancy can also estimate the size of the fetus according to the size of the pregnancy sac, the length of the head and buttocks, etc., with the help of the calculation formula software in the ultrasound, according to which calculating the expected date of delivery is also a more accurate method.
3. Other estimation methods
For natural pregnancies, pregnant women who cannot remember the last menstrual period or irregular menstruation, and have not undergone an early ultrasound examination (well, so there are pregnant women in MaDaha), we can also estimate the expected date of delivery based on the symptoms of pregnancy:
1. Estimation of the time from the beginning of morning sickness: morning sickness generally appears at the 6th weekend of pregnancy, that is, 42 days after the last menstrual period, and thus calculated backwards to 280 days is the expected date of delivery.
2. Calculated according to the date of fetal movement: generally fetal movement begins at 18 to 20 weeks after pregnancy. Therefore, the gestational age can be inferred according to the time of fetal movement, so as to determine the expected date of delivery. The specific calculation method is: the first mother is the fetal movement day plus 20 weeks; the menstrual mother is the fetal movement day plus 22 weeks.
In fact, the expected date of delivery is only a rough time, clinically full-term children refer to the gestational age between 37 and 42 weeks, about 80% to 90% of pregnant women give birth during this period, and only about 5% of pregnant women will give birth on the day of the expected date of delivery.
Finally, please take a rational view of the due date
The role of the expected date of delivery is to approximately estimate the date of delivery, not the exact date of delivery.
In fact, it is normal to give birth no more than 5% at the expected date of delivery, 3 weeks earlier than the expected date of delivery or within 2 weeks of delay.
Therefore, if you have not delivered by the expected date of delivery, you don't have to worry. Clinically speaking, full-term infants refer to gestational age between 37-42 weeks, and beyond 42 weeks are called expired infants. But a large proportion of babies will be born beyond the expected date of delivery, such as more than 41 weeks, if there is still no sign of childbirth at 41 weeks of pregnancy, they can be hospitalized for observation or give birth at the right time.