The transition to motherhood: the intersection of structural and temporal dimensions.

Prior work on the determinants of the 1st-birth process can be divided into 3 approaches: 1) time-series analysis focusing on description and determinants of trends; 2) cross-sectional studies examing childlessness or adolescent fertility; and 3) life-course studies dealing with the timing of fertility relative to other events. Drawing on these traditions, the conceptual framework places the 1st-birth process within, respectively, an aggregate-time dimension indicated by period or cohort, an individual-time dimension indicatedd by the respondent's age, and a social-structural dimension indicated by the respondent's spanning the 1955-1976 period, and examining conditional birth probabilities, the analysis incorporates each of these dimensions. Each dimension is important. Aggregate time exerts powerful and pervasive effects. Socio-structural variables have nonproportinal effects--tht is, their effects vary with time. The effects of the social-structural variables tend not to interact with the aggregate-time dimension. Finally, predictive power generally declines with inndividual time. author's modified