Effect of contraceptive pills on sexual activity in the luteal phase of the human menstrual cycle

The results of a double-blind placebo study reveal changes of sexual behavior of 51 women followed over three menstrual cycles. Differences in sexual activity during the luteal phase of the cycle (days 18 to 25) were noted. Sexual activity increased for women on contraceptive pills but not on placebo. After examination of the data, hypotheses were rejected that the difference was due to contraceptive pills directly affecting the woman's feeling state or overall activity level. The data are consistent, however, with the following: The presence of endogenous progesterone during natural cycles affects the male so that he does not desire coitus as frequently during the luteal phase. The absence of endogenous progesterone during pill cycles removes whatever restraint progesterone has on coitus. No other interpretation is consistent with the data derived from this study. The influence on the human male may operate via a pheromone as is the case with male rhesus monkeys.This research was supported by funds from the Carolina Population Center and the University Research Council.