Ages at reproductive health transitions in the United States

Women's and men's reproductive lives contain a number of milestones that mark changing life stages with different service needs. Specific events, such as the initiation of sexual intercourse and the completion of childbearing, often mark the beginning or end of stages during which different needs predominate. Knowing the typical ages at such events helps plan for services. Understanding the order in which these events typically occur allows us to estimate the length of these stages and to compare population subgroups' experiences of important life events. Most research in this area has generally focused on single transitions; for example, the rise in age at first intercourse which began in the 1990s (often described as a decrease in the proportion of adolescents who have had sex) has received a great deal of attention. However, a comprehensive assessment of these stages has not been performed since 1993 (using data collected in 1988) . An up-to-date examination is overdue. We use five National Surveys of Family Growth from 1982 to 2010, data from the 1995 National Survey of Adolescent Males, and event history techniques to calculate men's and women's median ages at various events – menarche, first intercourse, first contraceptive use, first cohabiting union, first marriage, and first birth. We will present data on the length of time between each milestone and compare the timing and length of these stages across generations and population subgroups. We will also present multivariate models of factors affecting the median age at selected events.