A Framework for Analyzing the Proximate Determinants of Fertility

Studies of the causes of fertility levels and their changes often seek to measure directly the impact of socioeconomic factors on fertility. Such procedures have a broad appeal to policymakers, offering as they do to pinpoint mechanisms susceptible to manipulation by official policy. Despite this appeal, such approaches are considerably more problematical in their application. Not infrequently, relationships are found to differ not only in magnitude but even in direction in different settings and at different times. Substantial insights can be gained if, in addition to the socioeconomic factors influencing fertility, the specific mechanisms through which these factors operate are identified. For example, the level of education of women is a socioeconomic indicator that is frequently found to be negatively related to fertility. A more detailed analysis may show that among educated women marriage is relatively late or the use of contraception more frequent, thus clarifying the relationship between education and fertility. In general, the biological and behavioral factors through which socioeconomic, cultural, and environmental variables affect fertility are called intermediate fertility variables. The primary characteristic of an intelmediate fertility variable is its direct influence on fertility. If an intermediate fertility variable, such as the prevalence of contraception, changes, then fertility necessarily changes also (assuming the other intermediate fertility variables remain constant), while this is not necessarily the case for an indirect determinant such as income or education. Consequently, fertility