Effect of occupation on menstrual cycle length: causal model.

The effect of occupational stress on menstrual cycle length was studied prospectively. The hypothesis that occupational stress has a direct or indirect effect on cycle length was tested using path analysis. Twice the number of women involved in active farm, craft, or household work had significantly longer cycle lengths than sedentary beedi workers and clerks. We conclude that occupational stress has a direct effect on menstrual cycle length and that that effect is similar to the effect of exercise on cycle length. The impact of longer cycles on fertility, fertility regulation, and natural family planning methods are also discussed.