Pharmacokinetics of progesterone a few other countries under the brand name Progestasert. It was marketed between 1976 and 2001. The IUD was never widely used due to a relatively high contraceptive failure rate of 2.9% and the requirement of annual replacement. It contained 38 mg progesterone and released 65 μg progesterone into the uterus per day (adding up to about 35 mg after one year). For comparison, a woman's body produces on average about 25 mg progesterone per day during the luteal phase. While effective as a form of contraception and for decreasing menstrual bleeding and discomfort, long-lived IUDs can fundamentally only deliver
Menstrual synchrony Menstrual synchrony Menstrual synchrony, also called the McClintock effect, is an alleged process whereby women who begin living together in close proximity experience their menstrual cycle onsets (the onset of menstruation or menses) becoming more synchronized together in time than when previously living apart. "For example, the distribution of onsets of seven female lifeguards was scattered at the beginning of the summer, but after 3 months spent together, the onset of all seven cycles fell within a 4-day period." Martha McClintock's 1971 paper, published in "Nature", says that menstrual cycle synchronization happens when the menstrual cycle onsets of two or