Our worlds just turned upside down…because there might not be such a thing as period syncing. Yep, that means if you and your BFF had matching menstrual cycles because you’re practically joined at the hip, it’s really just a coincidence.

The ovulation and period tracking app Clue, and the University of Oxford conducted a study to test the widely believed idea of period syncing, which actually didn’t have any prior scientific evidence.

The study began with 360 pairs of volunteers who spend an ample amount of time with each other (including roommates, siblings, friends, mothers, daughters, partners, and colleagues) while taking into account whether they live together and if they take any hormonal birth control.

They analyzed data over three consecutive menstrual cycles and found that 273 pairs actually ended up having a larger gap between cycle start dates at the end of the study than they did at the beginning of the study and only 79 pairs showed the opposite. The results shot down period syncing with an average difference of 10 days between the pairs’ cycles at the beginning of the study and 38 days at the end.

From our small pilot study of Clue users, our data scientists found that cycles between pairs and cohabiting individuals did not align. Our statistical evidence also indicated that cycles are actually more likely to diverge, rather than sync, over time.

So much for thinking that our time of the month was based on who we spend time with! What are your thoughts on this? Weigh in on the comments below!

xx, The FabFitFun Team