Abstract The Motherhood Biographies and Midlife Women’s Health R01 project maps how divergence in motherhood experiences contributes to growing midlife health disparities. About 85 percent of midlife women today are mothers, but pathways to motherhood—what we call motherhood biographies—are increasingly diverse across many dimensions relevant to health, including age at first birth and spacing of children. The parent project tests how motherhood biographies matter for midlife women’s health with a specific focus on race/ethnicity and socioeconomic status. We compare mothers and non-mothers as well as mothers with differing motherhood biography profiles using nationally representative data from the 1979-2018 waves of the National Longitudinal Study of Youth (NLSY79; N=4,951 women). We are testing the following aims with this diversity supplement and Brantley’s efforts focused on Aims 2 and 3: AIM 1: Identify how motherhood biographies—including childlessness—relate to midlife health. We are using information on motherhood status, number/spacing of children, age and marital status at each birth, fertility expectations, and pregnancy loss to identify motherhood biographies among women born 1957 to 1964 using Latent Class Analysis and alternative methods (e.g., Sequence Analysis). We are examining associations between motherhood biographies and physical, mental, and cognitive health and health behaviors at midlife. AIM 2: Identify how the impact of motherhood biographies on health depends on characteristics of child-mother relationship at midlife. Using mediation and moderation analysis, we are examining how child-mother ties in the mother’s midlife both explain and shape associations between the motherhood biography and midlife health. AIM 3: Identify the heterogeneous effects by educational attainment and race/ethnicity of motherhood biographies on midlife health. Given the education-motherhood and education-health linkages as well as the race/ethnicity- motherhood and race/ethnicity-health linkages, we are using moderation analysis to test whether motherhood status and motherhood biography associations have heterogeneous impacts on midlife health by educational attainment and race/ethnicity. Given Brantley’s interest, the proposed supplemental project will focus on the race/ethnicity components of Aims 2 and 3. In doing so, this sub-project directly contributes to parent project aims related to race/ethnicity and health disparities among women. Throughout the duration of the administrative supplement, Brantley will work with Thomeer (MPI), Reczek (MPI), and the other team members and mentors to conduct research for publications, presentations, and other research activates. Brantley will conduct analyses examining the dynamic and often complex relationship between motherhood biographies and health across and within racial/ethnic groups, specifically among Black mothers. The entire mentorship team will also assist Brantley in developing an NIH K01 a...