There are emergency contraceptives and short-acting contraceptives, long-acting contraceptives, etc. Pregnancy may not occur after twelve hours of taking emergency contraceptives and having intercourse, but it may occur if it is a short-acting contraceptive or a long-acting contraceptive. Emergency contraceptive pills contain a large amount of hormones and can be taken within 72 hours of having sex or before having sex. If you have intercourse twelve hours after taking the pill, pregnancy may not occur because the pill may not have been completely metabolized in the body and can still play a contraceptive role. However, if you are taking a short-acting contraceptive pill, due to the hormone dose is small, only through a short period of time and can not play a contraceptive effect, the long-acting contraceptive pill can only take effect after a week of taking the pill, so these two kinds of contraceptives to take twelve hours to have sex again, may be pregnant. If you have intercourse twelve hours after taking the pill, there is still a possibility of pregnancy. It is recommended that when symptoms similar to pregnancy such as delayed menstruation and breast tenderness occur, you should consult a doctor promptly to clarify the specific situation.