No, your period doesn’t sync with your roommate’s

A new study was performed by the period-tracking app Idea and the University of Oxford.


Sorry, ladies, but your roommate, sister, or female partner does not have a “alpha uterus” which is the cause of your menstrual cycle to match that of her. That’s according to a new study of the period tracking app Clue, which together with Oxford University scientists to determine whether there is any truth women’s periods synchronize when they spend a lot of time together, including living together, Live Science reports.

The researchers tapped 360 pairs of women who knew each other well, lived in the same city, and used Prompt; about 120 of those couples actually lived together.

After attending three consecutive menstrual cycles for all of the women, the scientists discovered that the sync-up story is not the pan: 360 pairs 273 pairs actually saw a larger gap between the start date of their cycles in the study’s end compared with the beginning.

Only 79 pairs saw their cycle start dates come closer together. And the cycles of the couples who lived together not fall into the rule more than the people that lived from each other: pairs with different cycles, 37% lived together, while of those whose start dates converged, only 24% lived together.

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The idea of this sync seems to have examined for the first time in 1971 (although that research was later slammed for its methodology), but several studies since have not been able to prove it.

So why do so many women in the vicinity insist that it happens? Designation data scientist Marija Vlajic tells the Guardian this belief may simply be a result of “information bias,” with “our brain is looking for patterns.” Vlajic adds that it’s also a “powerful” to think that you share of this monthly is done with other women.

“It nurtures a sense of connection, support, and sisterhood,” she notes. (An Arkansas mother and daughter certainly shared menstruation-themed bonding session.)

This article originally appeared on Newser: Busted: Ancient Myth About Women’s Periods

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