Ovulation occurs around May 18th for people who have their period on May 4th and have a menstrual cycle of about 28 days. Under the influence of hormones secreted by the ovaries, the process of follicles gradually developing into dominant follicles and being discharged is ovulation, which usually occurs about 14 days before the next menstrual period. Therefore, for a woman with a 28-day menstrual cycle and a period on May 4, the ovulation date will be around May 18, but there are individual differences in ovulation, and for women with long menstrual cycles, the ovulation date will be delayed appropriately. Women with fertility requirements can be guided to coitus under the guidance of a doctor by projecting the day of ovulation and ultrasound monitoring of follicular development to improve the chances of conception. Women with no fertility requirements should pay attention to contraception when having intercourse during ovulation.