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          Menstrual Synchrony - Myth or Fact?

It’s a common belief that women who live in close proximity to each other begin to have menstrual cycles that synchronize, or occur around the same time. In the 1970’s it was hypothesized by Martha McClintock that menstrual cycle synchronization would happen primarily because of pheromones, which then effect the hormones that control the menstrual cycle. 

After a substantial amount of studies, it was concluded in 2013 that menstrual synchrony probably doesn’t exist and that what is actually happening is “menstrual cycles of different frequencies repeatedly converge and diverge over time”

Why do we believe this in the first place?

Among traditional communities across the world, the concept that “menstruation should be in harmony with other rhythms”, such as the moon is central to many myths and rituals.  According to an ethnographic study of the Yurok people of California  “If a woman got out of synchronization with the moon and with the other women of the household, she could 'get back in by sitting in the moonlight and talking to the moon, asking it to balance her.’ ”  In modern times, this idea is perpetuated by the fact that observing “overlaps of menstrual cycles by chance is high.” 

Our period tracking gift, the Selene Beads bracelet is based on the idea that a woman’s menstrual cycle is similar to the phases of the moon.  In fact, the word “menstruation” is etymologically related to the word “moon”. The moon has a 29.5 day cycle, closely resembling a woman’s own menstrual cycle. However, according to studies mentioned earlier, if a woman finds that her cycle matches the phases of the moon (ovulating during the full moon, and menstruating during the waning moon), this is more of a temporary statistical probability than their body being locked into the same phase as the moon. 

What do you think?  Have you ever experienced menstrual synchrony with other women or with the phases of the moon?


Menstrual synchrony - Wikipedia