Medical Definition of Menstrual synchronization
Menstrual synchronization: A phenomenon that occurs when two or more menstruating women live or otherwise spend a lot of time together, in which the menstrual cycles of the women gradually become synchronized. The mechanism and reason for this effect is unknown, although research suggests that it may be due to the effects of female pheromones on other women's ovulation cycles.
Quick GuidePremenstrual Syndrome (PMS): Track and Prevent Symptoms
Subscribe to MedicineNet's Women's Health Newsletter