In recent decades, the most common means by which couples regulate fertility have changed from methods requiring control or cooperation by men, e.g., condoms, withdrawal and periodic abstinence, to those for which women bear primary responsibility e.g., virtually all-reversible modern methods.

Demographic literature is replete with observations of an inverse relation between certain attributes of modernity and family size (Thompson 1929; Notestein 1945; Coale and Hoover 1958; Leiberman 1980, Srinivasan 1986).