Abnormal bleeding after using the pill suggests three main possibilities: first, withdrawal bleeding. Contraceptive pills are mostly highly effective hormones, which cause an increase in hormone levels in women’s bodies after taking them, and after the metabolism of the pills ends, the hormone levels in women’s bodies will drop abruptly. So this fluctuation of hormone level will affect the patient’s endometrium, causing the patient’s endometrium to lose the support of high hormone level and appear to peel off and bleed. Secondly, it should be considered that the abnormal bleeding is caused by the endocrine disorder and menstrual disorder of women after taking the contraceptive pill. Birth control pills are mostly hormones, and these hormones are not added according to the normal hormonal fluctuations of women’s cycles. This untimely addition is likely to disturb the normal hormonal situation of women, so it will easily lead to endocrine disruption and cause bleeding. Third, to consider the contraceptive pill after the failure of contraception, intrauterine pregnancy, pre-eclampsia or ectopic pregnancy and lead to abnormal bleeding.