It is possible to get pregnant during intercourse after menstruation, and women can get pregnant during non-menstrual periods, so it is recommended that contraception must be used. The easiest time for a woman to get pregnant is around the time of ovulation, which is 14 days before the next menstrual period. The easiest time to get pregnant is three days before and two days after ovulation, while the probability of pregnancy is relatively low at other times. If a woman does not ovulate, it is impossible to get pregnant by having sex. However, a woman’s ovulation day is affected by various factors such as environment, emotions, mental stress and sleeping habits, which may result in unexpected ovulation. Because there is accidental ovulation, women may get pregnant if they are not during their menstrual period, as long as they have intercourse during non-menstrual periods, and contraception is recommended for all intercourse. If contraceptive measures are not taken before sex, it is recommended to take emergency contraceptive pills within 72 hours after sex.