There is almost no chance of pregnancy if you do not have intercourse during ovulation, except in the case of irregular menstruation and inaccurate calculation of ovulation, which may lead to pregnancy. If the menstrual cycle is regular, after the egg is ovulated, it will survive in the body for about 24 hours without fertilization, and then it will die. After the sperm is ejaculated into the vagina, it survives in the body for 2-3 days. If you have intercourse outside of the ovulation period, the egg has already died and the sperm cannot unite with the egg within the fallopian tube during the survival period, so intercourse when you are not ovulating usually does not lead to pregnancy. Therefore, if you want to use a safe period for contraception when your menstrual cycle is regular, you must calculate your ovulation time so that you can achieve the effect of contraception.