The distribution of coitus within the human intermenstruum.

Abstract

Daily records are the only acceptable basis for determining human coital rates. A re-analysis of such data presented by earlier writers and a study of new data suggest that within the intermenstruum (viz. the days on which there is no bleeding) the rate of coitus is highest immediately after menstruation ceases, declines thereafter and is lowest (within the intermenstruum) just before menstruation recurs.It is not clear whether there is a minor peak around ovulation time, but such a correlation, if it exists, is certainly not very powerful.The major cause of the higher coital rate after menstruation could be abstinence during menstruation and a post-menstrual feeling of release on the part of the woman.The fact that coital rates are largely independent of the time of ovulation might be due to their being largely determined by the male. In any case, it provides evidence for Morris's view that human sexuality has important evolutionary functions other than reproduction.