Over 1200 pairs of female monozygotic and dizygotic twins with regular menses reported on the amount of flow, severity of pain, and degree of limitation experienced during menstruation. Fifty-two percent of the women reported moderate or severe menstrual pain and these reports were fairly repeatable (0.62-0.80) over a 3-month interval. Heritabilities were 0.22 for flow, 0.38 for pain, and 0.36 for limitation. Covariations between menstrual symptoms and the symptoms and personality variables of state anxiety and depression and trait neuroticism were shown to be almost entirely genetic in origin. There was also gene action specifically affecting menstrual pain and also menstrual flow, but genetic variation in limitation was entirely due to genes also affecting flow, pain, and personality variables-neuroticism in particular.
- primary dysmenorrhea