Immunocontraception outcome has focused on human chorionic gonadotropin (hCG). hCG is not necessary for fertilization, but is secreted by embryos shortly thereafter. Therefore, immunity against hCG does not prevent fertilization. However, it was found that anti-hCG antibodies prevent marmoset embryos from implanting in the endometrium of their mother's uterus. The main function of hCG is to sustain the ovarian corpus luteum during pregnancy past the time it would normally decay as part of the regular menstrual cycle. For the first 7–9 weeks in humans, the corpus luteum secretes the progesterone necessary to maintain the viability of the endometrium for pregnancy. Therefore,
Progesterone vaginal ring Progesterone vaginal ring Progesterone vaginal ring, also known as progesterone-only vaginal ring, is a form of vaginal ring used for birth control when breastfeeding. Use can begin at four weeks and continue for at least up to a year following childbirth. Failure rates with usual use is about 1.5 per 100 women. It is used within the vagina with one ring lasting three months. The woman is able to place and remove the ring herself. Side effects include vaginal discharge and pain with urination. It does not appear to be associated with serious side effects. With use menstrual periods often