Contraceptive pills can only be taken once a month, and it is forbidden to take them more than twice. Because birth control pills are estrogen-progestin combination drugs, there will be some adverse reactions, for example, it will cause early or delayed menstruation, and there will be abnormal bleeding, that is, withdrawal bleeding occurs. When oral contraceptives are taken once a month, the menstrual cycle may be disrupted for three months. If more than one pill is taken orally, the irregularity of the menstrual cycle may last longer, resulting in menstrual disruption. At the same time, there is a 20% chance of failure after taking the pill, not 100% contraception. When your period is delayed, go to the drugstore and buy early pregnancy test strips to take a test. Try to use morning urine, which is more accurate and rules out pregnancy.