The normal sperm in the female body can survive for 2-3 days and has the ability to fertilize, while the egg only in 12-24 hours after ovulation fertilization may be, so for couples preparing to have children, learn to apply simple methods to determine the time of ovulation, master the initiative, timely intercourse is more conducive to early and successful pregnancy. A. Women with regular menstruation 1, ovulation time: about 14 days before the next menstrual flow. For example, if the menstrual cycle is 28 days, and the first day of menstruation is on January 24, then the next menstrual period will be on February 22, and then subtract 14 days from February 22, then February 8 is the day of ovulation. Women with shorter menstrual cycles will also ovulate earlier. If a woman has a 25-day menstrual cycle, she will ovulate roughly 10 to 12 days after her period. 2.Ultrasound examination: Go to the hospital 2-3 days before the calculated ovulation date for ultrasound examination to clarify the size of the follicle and the thickness of the endometrium. 3, urine ovulation test paper before ovulation, the female body secrete a hormone called luteinizing hormone (LH), its concentration rises rapidly, so you can buy a few ovulation test paper from the drugstore spare, in the 2-3 days before ovulation can be measured once a day in the morning and evening, if there are two bars – positive results, mostly within 24-48 hours will be ovulated, so ovulation test paper positive after the 2nd-3 days of intercourse is more likely to get pregnant. Second, the time of ovulation is not easy to determine for women with irregular menstruation, so you need to go to the hospital to determine it by ultrasound examination and blood hormone measurement.