Study Suggests Menstrual Cycle Syncing by Women Does Not Really Happen

A further proof on a common myth.


Do women’s menstrual cycles sync up over time if they are in close proximity to each other? Most of the women who live or work together, or just spend a lot of time together, find their menstrual cycle syncing. One study reported that 80% of women believe this phenomenon occurs and 70% of them find it pleasant to have this be the case. But the truth is controversial. Researchers suggest that this is nothing but a myth and it’s really just random chance when this synchronization is occurring.

Scientists conducted a test with women who use the Clue app. Clue app is a period tracker that discovers the unique patterns in women’s menstrual cycle. Every woman was in a close relationship with another woman over an extended period of time. Almost 1500 women responded to their request for assistance while 360 pairs of women were selected for inclusion.

As the app already track the information, all women need to share it with the researchers. Later, researchers looked back three menstrual cycles for each of the pairs if there was any alignment. They found that almost 273 of women already actually had diverged cycles whereas 79 had converged.

They noted, “Women who were living together were no more aligned than the other pairs. This is further proof that the entire idea is a myth with no basis in reality.”

Scientists suggest, “Regarding why so many women believe the myth, it has to do with chance and emotion—cycles last on average 28 days, which means a pair could, at most, be out of sync just 14 days. Simple math shows they would be out of sync on average just seven days, which could lead to a misperception of syncing, especially considering that the myth is so prevalent.”


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