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
Premenstrual dysphoric disorder ovulation suppression using contraception. Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS). Like PMS, premenstrual dysphoric disorder follows a predictable, cyclic pattern. Symptoms begin in the late luteal phase of the menstrual cycle (after ovulation) and end shortly after menstruation begins. On average, the symptoms last six days but can start up to two weeks before menses. The most intense symptoms occur two days before the start of menstrual blood flow through the first day of menstrual blood flow. The symptoms should cease shortly after the start of the menstrual period. The symptoms in PMDD can