The specific calculation of which day to conceive, you need to calculate the ovulation period according to the menstrual cycle, only in the ovulation period, the chances of pregnancy is higher, if the menstrual period is regular, from the next menstrual period counting forward to the 14th day is the day of ovulation, before and after the day of ovulation, the chances of pregnancy 1-2 days, according to the date of coitus to determine when the time to conceive. If your period is irregular, you can’t accurately calculate the date of conception, because irregular menstruation will also affect ovulation, you need to go to the hospital to do ultrasound, according to the size of the gestational sac to calculate the date of pregnancy, and then subtract the 14 days to consider is the time of conception, this is only an approximate judgment. Normally, the date of pregnancy is calculated from the first day of the last menstrual period, regular ultrasound during pregnancy to see if the gestational sac is in line with the size of the gestational week, if the gestational sac is small, it may be caused by malnutrition, it is best to timely dietary regimen and regular checkups.