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,
Menstrual cup investigated whether silicone menstrual cups are a viable alternative to tampons and found that approximately 91% of women in the menstrual cup group said they would continue to use the cup and recommend it to others. In a 1991 clinical study involving 51 women, 23 of the participants (45%) found rubber menstrual cups to be an acceptable way of managing menstrual flow. In a randomized controlled feasibility study in rural western Kenya, adolescent primary school girls were provided with menstrual cups or sanitary pads instead of traditional menstrual care items of cloth or tissue. Girls provided with menstrual cups had