There have been sweeping changes to marriage and family structures in the United States over the last several decades. Fertility rates dropped to historically low levels. Marriage rates declined while cohabitation became more common. Childbirth increasingly occurred outside of marriage as legal and cultural norms shifted. Women’s living arrangements at the time of their first birth have important implications for child and family well-being. Children born to married parents on average have access to more economic resources, and new mothers with a partner or spouse present generally have more emotional and financial support. In 2012, the Current Population Survey’s (CPS) June Fertility Supplement started collecting information on living arrangements of women aged 15 to 50 at the time of first birth. Using retrospective data on fertility history from the CPS’s June Fertility Supplement 2012–2024, this research brief describes women’s living arrangements (i.e., married, cohabiting, neither married nor cohabiting) at the time of their first birth from the early 1990s to the early 2020s, and shows how they differed by women’s educational attainment, race, and ethnicity.