Rape is not less frequent during the ovulatory phase of the menstrual cycle

Arguing that female adaptations reduce the likelihood of rape during fertile periods, Chavanne and Gallup (1998) cite two unpublished studies as evidence that rape is less frequent during the ovulatory phase, a claim subsequently repeated by other authors. Neither of the two studies in question (Rogel 1976; Morgan 1981) supports this conclusion. Moreover, analysis of conception rates reveals that the probability of conception following rape does not differ from that following consensual coitus. There is thus no evidence that rape frequency varies across the menstrual cycle in a manner reflecting female rape avoidance mechanisms. The contrast between evidence of the latter and the absence of epidemiological support may reflect differences between contemporary and ancestral societies.