Unequal Transitions to Adulthood: Widening Disparities in Age at First Union, Sex, and Birth in Many Low- and Middle-Income Countries.

Research on the timing of events during the transition to adulthood, such as first union, sex, and birth in low- and middle-income countries (LMICs), focused predominantly on measures of central tendency, notably median or mean ages. In this report, we adopt a different perspective on this topic by examining disparities in the timing of these events in 46 LMICs spanning four decades. Using Demographic and Health Surveys, we estimate ages at which 25 percent, 50 percent, and 75 percent of women have first union, birth, and sex. We compute interquartile ranges to measure within-country variation and disparities in the timing of sexual initiation and family formation. Variation in the timing of first union, birth, and sex generally increases as the median ages at these events increase. Disparities in the timing of first union and birth grew in West Africa and Latin America, and women who experience these events relatively early increasingly lag behind women who experience them relatively late. Documenting trends in measures of central tendency is insufficient to capture the complexity of ongoing changes because they mask growing disparities in the timing of family formation across many LMICs. These results are important for assessing progress toward the achievement of sustainable development goals related to the reduction of early marriages and pregnancies and highlight a need for more holistic approaches to measure the timing of family formation.