Culture and menstruation the ideal of synchronised tidal, lunar, menstrual and seasonal periodicities whose overall harmony (it is believed) confers spiritual power and fertility. To many, such cultural associations appear persuasive in view of the fact that in humans, the menstrual cycle quite closely approximates the moon's 29.5-day synodic cycle, unlike in chimpanzees (~36 days) or bonobos (~40 days). Statistical information from hunter gatherers is lacking, but where large-scale western studies focus on women's peak reproductive years—removing outlier values—the cycle length gravitates around 29.1–29.5 days, while the figure for women in their thirties shortens toward 28 days. In no extant human population has
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