If you've ever lived with other women, and none of you were on hormonal birth control, you may have discovered that your cycles slowly began to mimic each others. This is called menstrual synchrony, but many scientists will say that women who live together, menstruate together is hogwash. I've actually experienced this so there's got to be some truth to it.
In 1971, Martha McClintock studied 135 college women. She wrote down the starting date of their periods at three different times during the year. She discovered that women who lived in close-knit groups had their periods an average of 6 to 4 days apart during certain times of the year. It's said to be caused by pheromones, the release of chemical signals that influence behavior and physiology among people. Other studies conducted after this, however, showed no connection between women living together and their cycles synchronizing.
What do you think about menstrual synchrony? Have you ever lived with a woman (sister, mother, roommate) or group of women and noticed that you had your periods about the same time?