Introduction: The application of ovulation-promoting drugs during IVF, the possible control or change of menstrual cycle, and the difference between different ovulation-promoting protocols and embryo transfer protocols, some pregnant women who are expecting IVF are very confused about how to calculate the due date. How exactly should I calculate the due date for IVF? How to calculate the due date for IVF? The due date is the date when the pregnant woman is expected to give birth. The age of the fetus in the uterus is calculated in weeks, medically 4 weeks is 1 month, “October pregnancy” is actually 4*7*10=280 days. The expected date of delivery is calculated from the first day of the last menstrual period and pushed back about 280 days, or 266 days from the day of ovulation. For women with a stable menstrual cycle of 28 days, the following formula is generally used to calculate the expected date of delivery: the month in which the first day of the last menstrual period begins plus 9 or minus 3 is the number of months of the expected date of delivery; the number of days plus 7 is the date of the expected date of delivery. If the last menstrual period is January 1, 2016, month 1+9, date 1+7 , the expected date of delivery is October 8, 2016; if the last menstrual period is May 12, 2016, month 5-3, date 12+7 , the expected date of delivery is February 19, 2017. How to calculate the due date of IVF? 1. Calculation based on the day of transfer The ovulation period is the first day of the next menstrual period pushed forward by 14 days. For fresh embryo transfer in IVF cycle, the day of egg retrieval is equivalent to the day of ovulation, thus the first day of the last menstrual period should be 14 days before the day of egg retrieval. Regardless of the ovulation protocol used in the IVF cycle, the first day of the last menstrual period can be calculated by pushing the day of egg retrieval 14 days forward, with the month + 9, or -3, and the date + 7. Another way to calculate the due date is by the day of embryo transfer, so that it can be used regardless of the fresh cycle of egg retrieval, or the frozen embryo transfer cycle, and regardless of the ovarian stimulation protocol. In a natural pregnancy, the 14th day of menstruation is the day of ovulation. The egg is usually fertilized within 12-24 hours after ovulation and develops into an 8-cell oogenesis embryo in about 3 days and a blastocyst in 5 days. After IVF in vitro fertilization, the 8-cell stage embryo transfer or blastocyst stage transfer is equivalent to the day of ovulation +3 or +5 days, so the transfer day is shifted forward 14+3=17 days (8-cell stage transfer) or 14+5=19 days (blastocyst transfer) as the first day of the last menstruation, and the expected delivery date is projected according to this. The projection of the last menstrual period for IVF assisted conception is more in line with the medical standard for projecting the expected delivery date and is generally more accurate. (Figure: Embryo development process in vitro) 2. Early ultrasound examination after conception, such as ultrasound examination on day 45 of pregnancy and ultrasound examination on day 70 of pregnancy, can also be used to estimate the size of the fetus based on the size of the gestational sac and the length of the head and hips with the help of the calculation formula software in the ultrasound, which is also a more accurate method to calculate the expected date of delivery. 3, other methods of estimation: for natural pregnancy, can not remember the last menstruation or irregular menstruation, and did not go through the early ultrasound examination of pregnant women (well, such a big pregnant women are also there), we can also be based on the symptoms of pregnancy to estimate the expected date of delivery: from the time of the start of vomiting: vomiting usually occurs at the end of the sixth week of pregnancy, that is, 42 days after the last menstruation, so backwards to 280 days is the The expected date of delivery. Calculation according to the date of fetal movement: Generally, fetal movement starts at 18-20 weeks after pregnancy. Therefore, the week of pregnancy can be estimated according to the time of fetal movement, so as to determine the due date. The specific calculation method is: for first-time mothers, it is the day of fetal movement plus 20 weeks; for menstruating mothers, it is the day of fetal movement plus 22 weeks. In fact, the due date is only an approximate time. Clinically, a full-term baby is born between 37 and 42 weeks of gestational age, and about 80% to 90% of pregnant women give birth within this period, while only about 5% of pregnant women will give birth exactly on the due date. Therefore, all IVF pregnant mothers should not be too anxious about the due date, but should have regular checkups and go to the hospital immediately if symptoms of labor appear before 37 weeks, such as uterine contractions, vaginal bleeding, etc. If there are obstetric complications or complications such as twin pregnancy, gestational hypertension, gestational diabetes, etc., the doctor will decide whether to continue to keep the baby or terminate the pregnancy according to the actual situation. After entering 37 weeks, you should be ready to deliver at any time and let nature take its course. However, if there are no signs of labor after 41 weeks, you should be hospitalized for observation or terminate the pregnancy at the right time.