In 2017, there were 2.9 million heterosexual cohabiting couples (unmarried) with children under age 18.* This number has been steadily increasing: In 1996, it was 1.2 million. The number of all unmarried couples (with or without children) has increased even more during the same period.
Compared to their married counterparts, cohabiting couples with children tend to be younger, less-educated, lower-income, and hold less-secure employment. In cohabiting couples with children, just over two-fifths of parents are 25 to 34 years old, compared with around one-quarter of parents in married couples. About three in 10 parents in cohabiting couples are 35 to 44 years old, compared with four in 10 parents in married couples (Appendix 3).
Among women in cohabiting couples, 15 percent have no high school diploma, and another 35 percent have a high school diploma or a GED but no college-level education. Among women in married couples, 9 percent have no high school diploma, and 20 percent have a high school diploma but no college-level education (Appendix 3).
In cohabiting couples with children, 63 percent of women and 83 percent of men were employed in 2017, compared with 67 and 91 percent of women and men in married couples, respectively. In 7 percent of cohabitating couples with children, neither person was employed, compared with 3 percent among married couples with children (Appendix 3). Compared to children born to married parents, children born to cohabiting parents have lower rates of remaining in a stable family: Two-thirds experience family instability before age 12, compared with about one-quarter of children with married parents.
* Same-sex couples with children are not included in the analysis because, in some states, the distinctions between married and unmarried couples are unclear. Additionally, due to the small proportion of same-sex couples who have children, estimates are more susceptible to measurement error.
 Manning, W. D. (2015). Cohabitation and child wellbeing. Future of Children, 25(2), 51–66.