Menstrual cycle of progesterone, the uterine lining changes to prepare for potential implantation of an embryo to establish a pregnancy. If implantation does not occur within approximately two weeks, the corpus luteum will involute, causing a sharp drop in levels of both progesterone and estrogen. The hormone drop causes the uterus to shed its lining in a process termed menstruation. Menstruation also occurs in closely related primates (apes and monkeys). The average age of menarche is 12–15. They may occasionally start as early as eight, and this onset may still be normal. This first period often occurs later in the developing world
Menstrual extraction internationally. This method, another type of manual vacuum aspiration, is most often called menstrual regulation. As with ME, menstrual regulation, when desired as a method of controlling fertility, is performed very early in the menstrual cycle, earlier than a pregnancy test can be performed. One main difference between these two methods is the equipment used. While the Del Em was created such that one is able to put it together from individual pieces and it consists of three parts: the cannula with a one-way valve, a collection jar and the syringe, which are connected by plastic tubing; menstrual regulation is