There is a birth control ring can be pregnant, mainly due to the following reasons: first, the intrauterine device contraception, the main mechanism is the intrauterine sterile inflammation to prevent the fertilized egg to bed, so as to achieve the purpose of contraception. Due to the individual differences, very few people on the IUD after the sterile inflammation in the uterus can not prevent the fertilized egg to bed, so you will be pregnant. Second, the birth control ring in the intrauterine ectopic situation, the birth control ring after displacement does not play a corresponding contraceptive effect, so will also be pregnant. Third, the birth control ring expired, when the birth control ring must understand how long the birth control ring is valid, to the effective period if you want to continue to contraception must be replaced with a new birth control ring, if not replaced may lead to pregnancy, so in the time of the IUD must do a full understanding.