A Family Planning Hypothesis

An analysis of the hypothesis that the frequency of births in a population can be understood in terms of three factors that influence the desire for births: (1) a family size goal that is determined by characteristics of the environment; (2) the incidence of death among offspring; and (3) the effect of uncertainty in the family formation process. The hypothesis implies that these factors determine the average level of preferred birth rates and that they exert a systematic effect on actual births in following periods. These implications are tested by empirical evidence from Puerto Rico for the 1890s and 1950s by juxtaposing birth rates and environmental variables that include mortality, education, and the economic activity of women and children. The association between birth rates and environmental variables is consistent with the implications of the hypothesis. Other factors that are not accounted for by the family planning model are also considered as sources of variation in birth rates: urbanization, agricultural activity, age/sex, and marital status. These factors do not emerge as significant when the other variables of the family planning model are also considered.