1.How to calculate the gestational week for IVF patients: the last menstrual period is used to calculate. 2, IVF patients calculate the due date: the month of the last menstruation plus 9 or minus 3, the date plus 7, for example, the last menstruation is January 1, 2015, that is, the due date is calculated as: October 8, 2015. So how do IVF patients know their last menstrual period? ① For fresh cycle transfer patients, the last menstrual period is the transfer date minus 17 days, e.g. if the patient was transferred on January 30, 2015, the last menstrual period is January 13, 2015. ②For blastocyst transfer patients, since the embryo is developed to day 5 or 6, then the last menstrual period is the transfer date minus 19, for example, if the patient transferred blastocyst on January 30, 2015, the last menstrual period should be January 11, 2015. ③ Calculation of last menstruation for patients with thawing cycle transfer: same as above ④ Calculation of last menstruation for patients with artificial insemination: the date of artificial insemination minus 14 days, for example, if artificial insemination was performed on January 30, 2015, then the last menstruation would be January 16, 2015.