How to calculate the time of birth

Because it is difficult for every pregnant woman to accurately judge the time of conception, it is medically stipulated that the expected date of delivery starts from the first day of the last menstruation, and the whole pregnancy is 280 days, with 10 pregnancy months (28 days per pregnancy month). Pregnant women give birth within 38-42 weeks of pregnancy, all of which are full-term deliveries. Because each woman's menstrual cycle is different, it is normal that the expected due date differs from the actual expected due date by 1-2 weeks. The main calculation method is as follows:

According to the last menstrual calculation:

The month of last menstruation plus 9 or minus 3 is the estimated number of delivery months; Days plus 7 is the estimated delivery date. For example:

The last menstrual period of Ms. Zhang is1March 999 13, and the expected date of delivery is about199965438+February 20th.

Ms. Li's last period was May 28th 1999, and the expected date of delivery was about February 5th, 2000.

Pregnant women can also calculate backwards from the first day of the last menstruation to the 280th day, which is the expected date of delivery.

According to the date of fetal movement:

If you can't remember the date of your last menstruation, you can calculate it according to the date of fetal movement. Generally, fetal movement begins after pregnancy 18-20 weeks. The calculation method is: the primipara is the fetal movement day plus 20 weeks; The multipara is fetal movement day plus 22 weeks.

Calculated according to the basal body temperature curve:

The last day of the low temperature section of the basal body temperature curve is regarded as the ovulation date, and it is calculated from the ovulation date for 264-268 days, or 38 weeks.

According to B-ultrasound examination:

Doctors can estimate the gestational age and calculate the expected date of delivery by measuring biparietal diameter, head and hip length and femur length when doing B-ultrasound (this method is often used as B-ultrasound examination and diagnosis for doctors).

Calculation of morning sickness time:

The reaction of morning sickness usually occurs at the end of pregnancy, that is, 42 days after the last menstruation, so the estimated expected date of delivery is 280 days.