Being deaf or hard of hearing can be marginalizing and associated with inequitable health outcomes. Until recently, there were no U.S. population-based studies of pregnancy outcomes among deaf or hard of hearing women. In light of inconsistent findings in the limited available literature, this study sought to conduct a more rigorous study using population-based, longitudinal linked data to compare pregnancy complications, birth characteristics, and neonatal outcomes between deaf or hard of hearing and non-deaf or hard of hearing women.Researchers conducted a retrospective cohort study in 2019 using the Massachusetts Pregnancy to Early Life Longitudinal data system. This system links all Massachusetts birth certificates, fetal death reports, and delivery- and nondelivery-related hospital discharge records for all infants and their mothers. The study included women with singleton deliveries who gave birth in Massachusetts between January 1998 and December 2013.The deaf or hard of hearing women had an increased risk of chronic medical conditions and pregnancy complications including pre-existing diabetes, gestational diabetes, pre-eclampsia and eclampsia, and placental abruption. Deliveries to deaf or hard of hearing women were significantly associated with adverse birth outcomes, including preterm birth, low birth weight or very low weight, and low 1-minute Apgar score or low 5-minute Apgar score. No significant differences were found in size for gestational age, fetal distress, or stillbirth among deaf or hard of hearing women.Findings from this 2019 study indicate that deaf or hard of hearing women are at a heightened risk for chronic conditions, pregnancy-related complications, and adverse birth outcomes and underscore the need for systematic investigation of the pregnancy- and neonatal-related risks, complications, costs, mechanisms, and outcomes of deaf or hard of hearing women.