Taking birth control pills can also be pregnant may be improper time to take the pill, the drug is not absorbed and other reasons, the details are as follows: 1. Improper time to take the pill: short-acting contraceptive pills should generally be taken within five days of the onset of menstruation to start using, and even take 21-22 days, if there is a leakage of the service and did not make up for the service, there may be a contraceptive pill to get pregnant. Emergency contraceptive pills need to be taken within 72 hours after intercourse, and the earlier the better, the time of taking the pill if it has exceeded the effective contraceptive time, then the effect of the drug in the body will be weakened, and can not achieve the effect of contraception. 2. Drugs are not absorbed: contraceptive pills contain a large number of hormones, due to different personal constitution, after taking contraceptive pills, the body of the drug absorption is poor, will lead to the body can not reach the effective concentration of the drug, thus appearing to eat the pill will also be pregnant phenomenon occurs. You can choose to use condoms or birth control rings to achieve contraceptive effect according to your own situation. It is recommended to consult a professional doctor to choose the right contraceptive pill and not to buy it on your own. If you feel unwell, you should consult a doctor immediately.