If you have intercourse on the 18th day of your period, the chances of pregnancy are very high if you are not using proper contraception. Because in most cases a woman’s menstrual cycle lasts about 30 days, the eighteenth day of menstruation coincides with ovulation. During this period of time, coitus, no good contraception, if the patient does not have a requirement for pregnancy, it is necessary to take emergency contraceptive measures, such as oral contraceptive pills can be taken, you can also put a birth control ring to contraceptives; if the patient is within 72 hours of coitus, you can choose progestin or estrogen-progestin composite preparation of contraceptives; if it is within 120 hours, you can choose the composition of the contraceptive pill of mifepristone, you can also choose intrauterine placement of a birth control ring for contraception. If the patient has a request for pregnancy, it is possible to check the blood chorionic gonadotropin in about 10 days from the day of intercourse to determine whether or not the patient is pregnant.