How to calculate the number of months of pregnancy before the baby is born

Every pregnant woman wants to have a comprehensive understanding of the calculation method for the birth of a child in a few months of pregnancy. She wants to understand the calculation method for pregnancy and birth, and then calculate when she will start giving birth. The following content introduces this aspect in detail. If you want to understand it as soon as possible, you can see the detailed answer below.

Since it is difficult for every pregnant woman to accurately determine the time of conception, medical regulations stipulate that the expected date of delivery is calculated from the first day of the last menstrual period. The entire pregnancy period is 280 days, or 10 gestation months (each gestation month is 28 days). Pregnant women gave birth between 38 and 42 weeks of gestation, all of which were full-term. Since the length of each woman's menstrual cycle is different, it is normal for the estimated due date to differ from the actual due date by 1-2 weeks.

The main calculation methods are as follows:

1. Calculated based on the last menstrual period:

Add 9 or subtract 3 from the month of the last menstrual period to get the month of the expected delivery date; add 7 to the day of the last menstrual period to get the day of the expected delivery date. For example: Ms. Zhang’s last menstrual period was March 13, 2008, and her expected date of delivery is approximately December 20, 2008. The last menstrual period was May 28, 2008, so the expected date of delivery is approximately March 5, 2009. It can also be calculated backwards from the first day of the last menstrual period to the 280th day, which is the expected date of delivery.

2. Calculate based on fetal movement date:

If you can't remember the date of your last menstrual period, you can calculate it based on the date of fetal movement. Fetal movements usually begin between 18 and 20 weeks of pregnancy. The calculation method is: for primiparas, it is the day of fetal movement plus 20 weeks; for multiparas, it is the day of fetal movement plus 22 weeks.

3. Calculated according to the basal body temperature curve:

The last day of the low temperature segment of the basal body temperature curve is regarded as the ovulation day, and the ovulation day is counted back 264-268 days, or 38 weeks.

4. Calculated based on B-ultrasound examination:

When doctors perform B-ultrasound, they can measure the biparietal diameter of the fetal head, the crown-rump length and the femur length to estimate the gestational age and calculate the expected date of delivery (this method is mostly used by doctors for B-ultrasound diagnosis).

5. Calculate from the time when morning sickness starts:

Morning sickness usually occurs at the 6th week of pregnancy, which is 42 days after the last menstrual period. The expected date of delivery is 280 days after the last menstrual period.

The above introduces in detail the calculation method of how many months of pregnancy it will take for a baby to be born. For many pregnant women, they can have a comprehensive understanding of the above content and understand the calculation method of their own pregnancy and childbirth. They can use the above calculation method to calculate when they will start to give birth. After the calculation, they can make preparations for prenatal delivery.