“…Socio-economic factors have attracted considerable attention and have hindered elucidation of the race factor, in that apparent racial differences in birth weight have been attributed to some concomitant social variable (e.g. Crump, Horton, Matsuoka, & Ryan, 1957;Salber & Bradshaw, 1951). Naylor & Myrianthopoulos (1967) observed some effect on birth weight according to whether birth was urban or rural, the occupation of husband, family income, degree of education of mother, religion, and several other factors.…”