PROJECT ABSTRACT The proposed study will conduct a detailed examination of the impact of ableism on women with intellectual and developmental disabilities (I/DD) during pregnancy and the postpartum period, and will compare outcomes experienced by this group and their infants to those of peers without I/DD. Despite the growing number of individuals with I/DD giving birth and the substantial health needs and comorbidities present in this population, very little is known about the impact of ableism on healthcare access and service use among women with I/DD in the periods before and after delivery. Examining the healthcare experiences of these women in the Medicaid system in the US is a critical starting point. Medicaid funds almost half of births in the US and is among the only healthcare coverage options available to birthing people with disabilities including I/DD, most of whom do not have access to employer-sponsored health insurance. In addition, the Medicaid beneficiary population is diverse and includes birthing people from higher maternal risk groups, including Black women and women from other racial/ethnic minority groups who are disproportionately impacted by mental health diagnoses and maternal morbidity and mortality. We propose to use the latest available national Medicaid claims data (2016- 2023) to identify women with I/DD between 14 and 50 years of age who have given birth and are at risk for experiencing ableism and link them to their infants, who are also typically enrolled in Medicaid. We will compare pregnancy, childbirth, and postpartum health outcomes among women with I/DD compared to women without I/DD. By linking these women to their infants, we will assess the impact of ableism on neonatal and post-natal health outcomes, morbidity, and mortality. We will also link Medicaid information to other key data sources, including Census-based indicators of community-level social determinants of health and state Medicaid policy data to identify structural ableism and opportunities for systemic intervention. Using Medicaid- generated data that identifies service providers and designing data collection instruments aimed at assessing ableism, we will then survey and interview obstetric service providers to identify how attitudinal ableism impacts barriers and facilitators to service delivery and potentially modifiable components of healthcare access, referral, and service delivery (e.g., training, preparedness, communication) that may moderate the relationship between I/DD status and outcomes during pregnancy and postpartum. The information generated by this study is essential to identifying opportunities to address attitudinal and structural ableism to improve the system of care to meet the needs of the growing group of birthing women with I/DD and support outcomes for their infants. Completion of this study will result in the most substantive national work to date to identify modifiable policy, system, and provider factors to mitigate t...