How to Calculate the Estimated Due Date

The main methods for calculating the due date are as follows: 1. Last Menstrual Period (LMP) method: This is the most commonly used method. Starting from the first day of the pregnant woman's last menstrual period, add 9 months (if the month is less than March, add 9; if the month is March or later, subtract 3) and add 7 days. 2. Conception Date method: If the date of conception is known, the due date can be calculated by adding 38 weeks (i.e., 266 days) to the date of conception. This method is relatively more accurate but requires knowing the exact date of conception. 3. Ultrasound method: Through ultrasound examination at a hospital, doctors can estimate fetal age based on fetal development indicators such as biparietal diameter, crown-rump length, and femur length, and thereby determine the estimated due date. This method is particularly suitable for pregnant women with uncertain last menstrual period dates.