Calculation method of last menstruation: 1. Method of calculating the last menstruation of a friend who is assisted by artificial insemination: The date of insemination minus 14 days is the date of last menstruation. For example, if a woman has artificial insemination on March 18, her last menstrual date is March 4. (1) If the embryo is transferred on the 3rd day, the last menstrual date is the date of transfer minus 17 days. For example, if a woman’s transfer date is March 18, her last menstrual period will be March 1. (2) If day 5 and day 6 blastocysts are transferred, the last menstrual date is the transfer date minus 19 days. For example, if the transfer date is March 25, the last menstrual period will be March 6. Calculation of due date: All due dates are calculated by adding 9 or subtracting 3 to the month of the last menstrual period and adding 7 to the date of the last menstrual period. For example, if a woman’s last menstrual period is March 11, 2015, her due date will be approximately December 18, 2015. A woman’s last menstrual period is May 11, 2015, which means that the date of conception and delivery is approximately February 18, 2016.