Is pregnancy calculated from the day of intercourse?
The number of days of pregnancy is not calculated from the day of intercourse, but from the first day of the last menstrual period, which is the day the last menstrual period began. This method can be used to calculate the number of days of pregnancy for women with regular menstrual cycles and women with menstrual cycles of around 28-35 days. In addition, to obtain accurate data, we usually perform an ultrasound scan to calculate the actual number of days of pregnancy based on the size of the gestational sac or the length of the embryo.
1. There are certain rules for calculating the number of days of pregnancy based on the last menstrual period. Generally, it is calculated based on the menstrual cycle. Add 9 or subtract 3 from the month of the last menstrual date to get the expected delivery month. Add 7 to the day of the last menstrual date to get the expected delivery date. For example, if the last menstrual period was on March 13, 2008, the expected delivery date is approximately December 20, 2008. If the last menstrual period was on May 28, 2008, the expected delivery date is approximately March 5, 2009. Alternatively, you can count backward from the first day of the last menstrual period to the 280th day to get the expected delivery date.
2. Calculation based on the date of fetal movement: If you can't remember the exact date of your last menstrual period, you can also calculate based on the date of fetal movement. Fetal movement generally begins between 18-20 weeks of pregnancy. The calculation method is: for first-time mothers, add 20 weeks to the date of fetal movement; for multiparous women, add 22 weeks.
3. Calculation based on the basal body temperature curve: There are other methods to calculate the number of days of pregnancy, such as using the basal body temperature curve. Take the last day of the low-temperature period as the ovulation day and count backward from the ovulation day for 264-268 days, or add 38 weeks.
4. To determine the exact number of days of pregnancy, a B-ultrasound scan is usually performed at the hospital. By measuring the biparietal diameter, crown-rump length, and femur length of the fetus through the B-ultrasound scan, the gestational age can be estimated, and the expected delivery date can be calculated accordingly (this method is mostly used by doctors for B-ultrasound diagnosis).
