In the Fertility of Women in the United States: 2012 report, we use June 2012 Current Population Survey data to examine family instability. A common definition of family instability is considered to be changes in the composition of a family that are not caused by either birth or death — such as divorce.  Studying instability is important because other research has linked family instability to negative outcomes for both adults and children.

New questions were added to the June 2012 Current Population Survey Fertility Supplement asking about women’s relationship status — married or cohabiting — at the time of their first birth. The data from these questions allow us to look at trends in nonmarital births over time, as well as explore the characteristics of women who have had nonmarital births.

To examine the implications of first-birth circumstances for later familial instability, we used logistic regression models to predict, based on her relationship status at first birth, the likelihood that a woman was married at the time of the survey, as well as the likelihood that she lived in a blended family. By blended family, we mean that she had a stepchild in the home or had a spouse or partner present who was a stepfather to at least one of her children.

After accounting for women’s demographic characteristics (such as their race, nativity and number of children ever born), we found that women who were not married when they had their first child were less likely than women who were married when they became mothers to be married at the time of the survey. This suggests either that women who were not married at their first birth were less likely to ever marry or that their marriages did not last.

Furthermore, among women who were living with a child, women who were not married at their first birth were more likely to live in a blended family at the time of the survey than women who were married when they became mothers. This suggests that women with nonmarital first births experience higher family turbulence than women whose first birth was in marriage.

Taken together, these data suggest that women with nonmarital first births may face greater family instability than women with marital first births do.