From the first day of the last menstrual period (LMP), subtract 3 months or add 9 months, and add 7 days.

The entire gestation period is calculated from the first day of the last menstrual period, which is 280 days, or 40 weeks.

If gestation reaches 28 weeks (196 days) or more, the process from the onset of labor to delivery is called delivery.

Delivery occurring between 28 weeks and less than 37 full weeks (196-258 days) is termed premature delivery.

Delivery occurring between 37 weeks and less than 42 full weeks (259-293 days) is termed term delivery.

Delivery occurring at 42 weeks (294 days) or more is termed postterm delivery.

Induction of labor may be routinely performed for pregnant women after 41 weeks.

English Name: Expected Date of Confinement (EDC)

If the first day of the last menstrual period is September 10, 2007, the expected date of confinement would be June 17, 2008. If the woman only knows the lunar date, it should be converted to the Gregorian calendar to calculate the expected date. The actual delivery date may differ from the calculated expected date by 1-2 weeks. If the woman cannot recall the date of the last menstrual period or is pregnant during the breastfeeding period when menstruation has not resumed, the expected date can be estimated based on the timing of early pregnancy symptoms, the onset of fetal movement, fundal height, and ultrasound measurements such as gestational sac size (GS), crown-rump length (CRL), biparietal diameter (BPD), and femur length (FL).