Poster #129 - What Changed between Gen X and Millennials? Investigating Recent Declines in U.S. Fertility

• In Event: Friday Poster Reception

Abstract

After remaining stable for decades, the U.S. total fertility rate has recently decreased dramatically, from 2.1 in 2007 to 1.6 in 2021. Despite extensive work investigating this decline, researchers remain baffled as to its cause, finding that economic and policy factors are unlikely explanations for the large and extended fall in birth rates. The inability to identify specific reasons for the decline in period fertility rates has led some researchers to speculate that the decline in fertility may be a result of changes in cohort fertility behavior, perhaps reflecting “shifting priorities across recent cohorts of young adults” (Kearney et al 2022). This paper is the first to specifically explore this cohort-based hypothesis.

We show that recent declines in U.S. fertility are due to changes in fertility across cohorts and perform an initial investigation into the reasons for these changes. We identify an apparent generational shift in fertility patterns between Generation X (born 1965-1979) and Millennials (born 1980-1995). By examining cohort fertility using data from the Human Fertility Database, we show that the total fertility of Generation X (i.e., completed fertility between ages 15 and 45) was nearly constant or even increasing across its member birth cohorts. In contrast, Millennial cohorts display much lower fertility than Gen X, particularly for younger cohorts of that generation. As Millennials have not yet reached age 45 and completed their fertility, they still may “catch up” with Gen X if their fertility rates in their 30s and early 40s are high enough. However, we show that to do so, Millennials must experience fertility rates at older ages higher than ever before recorded in the United States.

We then investigate the potential role changes in partnering may play in driving this decrease in fertility across Gen X and Millennials. We show a changing relationship between marriage, cohabitation, and fertility onset between the two generations using data from the National Survey of Family Growth. For both Gen X and Millennials, declines in marriage rates were largely offset by increases in cohabitation. While fertility onset (i.e., the age at first birth) remained relatively unchanged for women who marry across the two generations, the fertility onset of women who cohabit with a partner but do not marry changed significantly between Gen X and Millennials. For Gen X, cohabiting women experienced increasing fertility across its member cohorts—keeping overall completed fertility stable by offsetting the corresponding decline in marriage. However, cohabiting Millennial women are increasingly less likely to experience fertility onset before age 30, driving the decline in fertility across the two generations. Our work points to understanding the changing fertility and marital intentions of cohabiting couples as being key to untangling the drivers of recent U.S. fertility decline.

Reference

Kearney, M.S., Levine, P.B. and Pardue, L., 2022. The puzzle of falling US birth rates since the Great Recession. Journal of Economic Perspectives, 36(1), pp.151-176.

Author

• Janna Johnson, University of Minnesota
  Presenting Author