The effect of marathon training upon menstrual function.

Detailed questionnaires were distributed to the 1,841 women who entered the 1979 New York City Marathon; the questions pertained to obstetric, gynecologic, and athletic histories, as well as height and weight. The incidence of oligomenorrhea/amenorrhea among the 394 respondents was 24% during training and 19% prior to training. The incidence of infertility among respondents was 10%. Of those women who had had regular menses prior to training, 93% continued to have regular menses during training. Amenorrheic women were significantly lighter (P less than 0.005) than regularly menstruating women and had significantly lower weight/height ratios (P less than. 0.0005). The best predictor of a women's menstrual pattern during training was her pretraining menstrual pattern. Thinness was associated with amenorrhea, regardless of training.