Measuring Ages at Reproductive Health Transitions

Lawrence B. Finer, Alan Guttmacher Institute
Jacqueline E. Darroch, Alan Guttmacher Institute

Key reproductive health events, such as first intercourse, typically mark different life stages with varying service needs. Thus, it is useful to know the ages at which individuals typically experience such events. We use National Surveys of Family Growth (NSFG) from 1982, 1988 and 1995 to investigate the feasibility of using cross-sectional and survival methods to calculate median ages at women's key events: menarche, first intercourse, first pregnancy, first marriage, first birth, completion of desired fertility, and infertility/sterility. Hazards models are also used to compare ages across demographic subgroups. Cross-sectional estimates are useful for comparing different measures and can be calculated for more events. Life-table estimates are useful for cohort and subgroup analyses, and the life-table approach produces small but notable differences in estimates compared with the cross-sectional approach. Women are at risk of unintended pregnancy for an increasing proportion of their reproductive years, implying a growing need for services.