86 Menstrual Synchrony

Based on research by Martha McClintock, (1971). Psychology Science Minute written by Juanita N. Baker, Ph.D..

How can we trust science when it seems to keep changing its mind? If new research seems plausible, and is amazing and exciting, often the first published study gets attention and the public as well as professionals believe the results, especially when published in prestigious scientific journals.  However, science is a method for correcting errors, where scientists scrutinize studies and look for other explanations for results.  Also, other scientists must repeat the original research before results are fully accepted.

In 1971, Martha McClintock found that when women live close together, their menstrual cycles would move to occur closer to the same time.  She hypothesized women would become in sync with each other through sensing each other’s pheromones.  However, since her study, other researchers identified methodological flaws, questioned proposed explanations, and completed refined studies that failed to find menstrual synchrony. Menstrual cycles and days between cycles vary in length, therefore women’s cycles will likely change and overlap over months. Intimate information is not usually shared; so many women may believe their cycles are in sync when discovering a friend is also menstruating.

Let’s conclude from these studies, to always scrutinize new research. Wait for verification by other scientists before acting on it.


Harris, A. L. & Vitzthum, V. J. (2013). Darwin’s Legacy: An Evolutionary View of Women’s Reproductive and Sexual Functioning. Journal of Sex Research, 50 (3–4): 207–46. doi:10.1080/00224499.2012.763085. PMID 23480070.

McClintock, M. K. (1971). Menstrual synchrony and suppression.  Nature, Vol 229(5282), Jan 1971, 244-245. doi: 10.1038/229244a0

Wilson, H., Kiefhaber, S., & Gravel, V. (1991). Two studies of menstrual synchrony: Negative results. Psychoneuroendocrinology, 16 (4): 353–9. doi:10.1016/0306-4530(91)90021-K. PMID 1745701.

Ziomkiewicz, A. (2006). Menstrual synchrony: Fact or artifact? Human Nature, Vol 17(4), 2006, 419-432. doi: 10.1007/s12110-006-1004-0

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