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
Heavy menstrual bleeding up to 50%. This may be combined with hormonal medication previously mentioned. Anti-inflammatory medication like NSAIDs may also be used. NSAIDs are the first-line medications in ovulatory heavy menstrual bleeding, resulting in an average reduction of 20-46% in menstrual blood flow. For this purpose, NSAIDs are ingested for only 5 days of the menstrual cycle, limiting their most common adverse effect of dyspepsia. A definitive treatment for heavy menstrual bleeding is to perform hysterectomy (removal of the uterus). The risks of the procedure have been reduced with measures to reduce the risk of deep vein thrombosis after surgery, and the