This topic constantly belies the fact that everywhere it is discussed is a sausage fest. Pregnancy, childbirth, and nursing are energetically demanding, physica

This topic constantly belies the fact that everywhere it is discussed is a sausage fest. Pregnancy, childbirth, and nursing are energetically demanding, physically unpleasant, dangerous things to do. Sexually reproducing creatures nonetheless have a strong instinct to do it because we wouldn't exist otherwise, but education brings increasing choices, increasing opportunities to do anything else, and once you have that choice, at least some birthing people are going to choose something else at least some of the time. Ergo, you get a marginal effect.