Change in the stability of U.S. marital and cohabiting unions following the birth of a child

Kelly Musick, Cornell University
Katherine Michelmore, Cornell University

The share of births to cohabiting couples has increased dramatically in recent decades. These families tend to be less stable than those formed in marriage, with potential implications for the well-being of parents and children. We use data from the 1995 and 2006-10 National Survey of Family Growth (NSFG) to: 1) describe change in the characteristics of couples having children together, paying attention to trajectories of cohabitation and marriage around the couple’s first birth; 2) compare change in union stability following the birth of a child across four distinct union-birth trajectories; and 3) illustrate change in patterns of stability using simple simulations. Relying on multivariate event history models, we find evidence of a weakening association between cohabitation and instability, given marriage occurs at some point before or after the couple’s first birth. The more recent data show statistically indistinguishable separation risks for couples who have a birth in marriage without ever cohabiting, who cohabit and then have a birth in marriage, and who have a birth in cohabitation and then marry. Cohabitating unions with children are significantly less stable when de-coupled from marriage, although the parents in this group also differ most from others on observed (and likely, unobserved) characteristics.