“…Improved sanitation and health care have also been important developments as they lower infant mortality, obviating the demand for "insurance" births (Davis, 1963;Hirschman & Guest, 1990;Singh, 1994). Perhaps most important, however, are the effects of the vast expansion of school systems on female education, which has led to marriage postponement, empowerment of women to adopt "western" values of smaller families, and improved use of fertilityregulating methods (Caldwell, 1980;Diamond, Clements, Stone, & Ingham 1999;Dreze & Murthi, 2001;Easterlin & Crimmins, 1982;Hirschman & Guest, 1990;Kravdal, 2000;United Nations, 1995a, b, c). Each of these processes operates through proximate behavioral and biological factors regulating fertility: fecundity or potential fertility, fertility preferences, and the implementation of those preferences through formation of unions, use of contraceptives, and birth spacing (Bertrand, Salazar, Mazariegos, Salanic, Rice, & Sow, 1999;Davis, 1963;United Nations, 1987, 1995aWarren, 1987).…”