The Yohtek contraceptive pill works by altering the thickness of the uterine lining, which prevents the fertilized egg from settling, and can prevent the ovaries from ovulating, thus achieving contraception. A common clinical side effect of the oral contraceptive pill Yuting is that it can cause withdrawal bleeding. Usually when you take Yutting contraceptive pill in the first half of menstruation, the endometrium will be thickened due to the action of exogenous progesterone, and withdrawal bleeding will occur about 3-5 days after stopping the pill. When endogenous progesterone increases, the endometrium repairs again and the bleeding stops on its own. Often people do not have withdrawal bleeding when they take the Yohtek pill during the second half of their period, mainly because the endometrium thickens during the second half of the period due to the formation of the corpus luteum, so there is no withdrawal bleeding. But there is no withdrawal bleeding, does not mark the success or failure of contraception, so the oral contraceptive effect of Yutting contraceptive pill is good, but not to achieve 100% contraception.