Dear Hopes She's Right,

You and your mother are not the only ones debating the facts surrounding menstrual synchrony (the tendency of women's menstrual cycles to converge). A heavy flow of controversy has existed ever since researcher Martha McClintock first reported the phenomenon in 1971 based on a study published in the scientific publication, Nature, that she conducted in a women's residence hall.

Some scientists claim that women who live together and/or have close emotional bonds (e.g., sisters, mothers and daughters, lovers) have periods that eventually start to coincide or overlap. Other studies have found no evidence of menstrual synchrony in these same groups. Because no research has been able to pinpoint the potential cause(s) of synchrony, other factor(s) may influence the timing of women's periods (e.g., stressor levels, sexual activity, ability to sense pheromones), confusing researchers and roommates alike.

Until more is known about the wonders of menstruation, a definitive answer is unlikely. In the meantime, you and your mother can see what happens within your own group(s) of women and read about McClintock's research and other menstruation matters at the Museum of Menstruation and Women's Health web site.

Alice

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