The chances of getting pregnant are greatest when you have intercourse on the day of ovulation during the ovulation period. If a woman’s menstrual cycle is 30 days long, days 10-20 of the menstrual period are ovulation days, and the chances of pregnancy are relatively high during this time. The 16th day of menstruation is the day of ovulation, and the chances of pregnancy are highest during this time. However, the chances of pregnancy do not necessarily mean that the patient will get pregnant, if you want to maximize the chances of conception, it is recommended to use ultrasound to monitor ovulation. If the woman ovulation is normal, when the ultrasound suggests that the follicle development to 1.8cm can choose to cohabit, and can be every other day cohabit, 2-3 times in a row, usually will not miss the time of ovulation. Because sperm can survive for 72 hours, as long as the patient ovulates between coitus or within 3 days after coitus, there is a chance of pregnancy.