In order to calculate the ovulation date, it is necessary to consider the regularity of a woman’s menstrual cycle, which should be analyzed on a case-by-case basis and not be generalized. If a woman has a regular menstrual cycle once a month and her last menstrual period is on the 13th, the ovulation day of the month is usually the 30th, and the 4-5 days before and after the ovulation day belong to the fertile period. If the next menstrual period is on the 13th of the following month, then the 29th is the day of ovulation, and the 3-4 days before and 3-4 days after are the ovulation period. In other words, 1 week before the menstrual period and 1 week after the menstrual period is cleared are relatively safe periods. For women with irregular menstrual cycles or other gynecological problems, they can detect ovulation by themselves with ovulation test strips. Therefore, women who want to get pregnant can choose to have intercourse during ovulation to increase their chances of getting pregnant. If you don’t want to get pregnant, you can choose to have intercourse during the safe period, but you need to take contraceptive measures to prevent unwanted pregnancy.