The due date is mainly calculated from the first day of the last menstrual period of a woman, and for women with regular periods, the due date is calculated based on the 28-day menstrual cycle, i.e. the month of the last menstrual period minus 3 or plus 9, and the date plus 7. Therefore, if you are pregnant in November, the due date for the last menstrual period from November 1 to 24 is August 8 to 31 of the following year. In the case of women who have irregular periods or who do not remember their last menstrual period, the expected date of delivery will also be early or late due to the early or late menstrual cycle, and the expected date of delivery can be estimated by the size of the gestational sac under the earliest ultrasound. In addition, pregnant women should be aware that once the urine HCG is positive, they should go to the hospital for checkups and have pregnancy tests on schedule as required by the maternal and child health handbook to actively prevent complications and complications during pregnancy.