The contraceptive principle of the IUD is clinically based on the following points: First, the IUD will produce sterile inflammation in the endometrium and prevent the fertilized egg from being laid, thus achieving the contraceptive effect, which is the first principle. Second, some birth control rings with drugs, such as the current Manuel ring contains highly effective progestin, highly effective progestin can counteract estrogen, will make the uterine lining thinning to prevent the fertilized egg to bed, resulting in the phenomenon of non-pregnancy, this is the contraceptive principle of the contraceptive ring. There is also a copper birth control device, which mainly affects the sperm acquisition and can increase the effectiveness of contraception.