When do you start counting weeks of pregnancy?

As the old saying goes, pregnancy lasts for ten months and delivery takes one day. However, many people do not know how to calculate the pregnancy cycle, so they are not clear about the calculation of the ten months of pregnancy. Today we will look at how to calculate the pregnancy time.

Many societies and their laws divide pregnancy into three trimesters. There is a high chance of miscarriage in early pregnancy. In the late stage, the fetus develops to the point where it can be tracked and detected. The late fetus begins to have the ability to survive outside the mother's body. Because of this ability, many laws and customs consider the fetus at this stage to be a person.

Calculate the expected date of delivery (calculate the time of pregnancy)

Because every pregnant woman cannot accurately tell the time of pregnancy, medicine requires that the expected date of delivery be calculated from the first day of the pregnancy. The entire pregnancy period is 280 days, 10 gestational months (each gestational month is 28 days). Pregnant women give birth between 38 and 42 weeks of pregnancy, all of which are full-term. Because each woman's menstrual cycle is of different length, it is normal for the estimated due date to differ from the actual due date by 1-2 weeks. The key calculation methods are as follows:

1. Calculate based on the expected date of delivery

Add 9 or subtract 3 from the month of the expected date of delivery to get the month of delivery; add 7 to the day of delivery to get the day of delivery. For example: Ms. Chen's due date is March 13, 2008, and her due date is approximately December 20, 2008. Ms. Chen's due date is May 28, 2008, and her due date is approximately March 5, 2009. You can also calculate backwards from the first day of the due date to the 280th day, which is the due date.

2. Calculate based on the baby's fetal movement date

If you can't remember your due date, you can calculate it based on the baby's fetal movement time. Generally, fetal movement begins between 18 and 20 weeks of pregnancy. The calculation method is: for first-time mothers, it is the day the baby moves plus 20 weeks; for first-time mothers, it is the day the baby moves plus 22 weeks.

3. Calculate based on the basic body temperature curve

The last day of the ultra-low temperature segment of the basal body temperature curve is taken as the ovulation period, and 264-268 days are counted backward from the ovulation period, or 38 weeks are added.

4. Calculation based on B-ultrasound examination

When doctors do B-ultrasound, they can measure the biparietal diameter of the fetal head, the brachiocephalic diameter and the length of the femoral head to estimate the gestational age and calculate the date of delivery (this method is mostly used as a doctor's B-ultrasound examination for diagnosis).

5. Calculate from the time when morning sickness begins

Morning sickness usually occurs on the 6th week of pregnancy, which is 42 days after the expected date of delivery, and then counting backwards to 280 days is the due date.

Detection and determination of time

The beginning of pregnancy can be determined in a number of ways. One is to detect the male hormones produced by newly formed embryos. Clinical urine and blood tests can detect pregnancy within 6-8 days after conception. Home urine tests usually take 12-15 days to detect effectively. Both of these methods can only detect pregnancy but cannot tell the time of pregnancy. Pregnancy can also be confirmed by the cessation of menstruation. The menstrual period stops earlier than any early pregnancy symptoms (such as morning sickness). In fact, doctors usually calculate the date of pregnancy (that is, the "age" of the test tube embryo) based on the first day of the previous menstrual period reported by the woman. Unless you have very infrequent sexual intercourse, it is difficult to know the exact time of conception.

The above provides a variety of methods for everyone to calculate the pregnancy cycle. Everyone can choose a method that they are more interested in. If you really can't calculate it clearly, the hospital prenatal check-up will also provide more detailed pregnancy time.