The 12th day after menstruation is not safe, and contraception is needed for intercourse. Women with regular menstrual cycles, the day of ovulation is about 14 days before the next menstrual period, and 4 days before and 5 days after the day of ovulation belong to the ovulation period, for women with a 28-day menstrual cycle, the end of the 12th day of menstruation is still in the period of ovulation, so this time coitus is not safe, and there is a possibility of pregnancy. Safe period refers to the time other than ovulation and menstruation, but because ovulation is affected by a variety of factors such as mood, temperature and so on, safe period contraception is unreliable, very easy to lead to unwanted pregnancy. For women who do not wish to have children, they can choose safe and effective contraceptive measures under the guidance of a doctor, such as taking short-acting contraceptive pills, placing intrauterine devices, condoms, etc., in order to avoid unwanted pregnancies.