Lunar effect purported lunar-lunacy connection, and at least 20 published studies on the purported lunar-birthrate connection. This has allowed several extensive literature reviews and meta-analyses to be produced, which have found no correlation between the lunar cycle and human biology or behavior. Examples of the belief have been found in ancient Assyrian/Babylonian writing. Claims of a lunar connection have appeared in the following contexts: It is widely believed that the Moon has a relationship with fertility due to the corresponding human menstrual cycle, which averages 28 days. However, no connection between lunar rhythms and menstrual onset has been conclusively shown to exist,
Menstrual synchrony more women become closer together in time than they were several months earlier.. After the initial studies, several papers were published reporting methodological flaws in studies reporting menstrual synchrony including McClintock's study. In addition, other studies were published that failed to find synchrony. The proposed mechanisms have also received scientific criticism. A 2013 review concluded that menstrual synchrony likely does not exist. Martha McClintock published the first study on menstrual synchrony among women living together in dormitories at Wellesley College, a women's liberal arts college. McClintock hypothesized that pheromones could cause menstrual cycle synchronization. However, other mechanisms have been proposed,