The residual time of birth control pills in the body is about 3 days, and the residual time varies due to individual differences. However, the effects of birth control pills on the body are far more than 3 days, because oral contraceptives are mainly used to inhibit ovulation and change the thickness of the uterine lining to achieve the purpose of contraception. When taking short-acting birth control pills, the endometrium will be abnormally thickened, which will prevent the fertilized egg from implanting. When taking short-acting birth control pills, the endometrial lining of the uterus will become thinner, which will also prevent the fertilized egg from implanting. Therefore, when taking birth control pills, ovarian ovulation is inhibited, so that the natural menstrual cycle and the function of ovarian ovulation are affected to a certain extent. If you want to plan a pregnancy after taking oral contraceptives, it is best to think about it after 3 months.