Stable aggregate fertility in a time of family change: a decomposition of trends in American fertility, 1970-1999.

Population-level birth rates in the United States were largely stable between 1970 and 1999. This stability contrasts with rapid change in marriage rates and fertility timing during the same period. In this article, I use decomposition techniques to analyze this seeming paradox. I decompose the general fertility rate into four components: age distribution, marital status, age-specific nonmarital fertility, and age-specific marital fertility. Absent other changes, declining time spent married would have led to substantial decline in fertility. Several factors combined to counterbalance these changes in marital behavior. Among white women in the 1970s and 1980s, marital fertility rates increased at older ages, consistent with a scenario in which women postponed both marriage and childbearing; increased nonmarital birth rates during this period were not a driving factor in overall fertility trends. Increased nonmarital fertility was more important in compensating for declining time spent married among African American women and among white women in the 1990s.