Key PointsQuestionWhat were trends of and risk factors associated with maternal mortality and severe maternal morbidity (SMM) among women giving birth in US hospitals during 2008 to 2021?FindingsIn this cross-sectional study of more than 11.6 million delivery-related hospitalizations, regression-adjusted in-hospital maternal delivery-related mortality per 100 000 discharges declined from 10.6 to 4.6, while the prevalence of SMM per 10 000 discharges increased from 146.8 to 179.8 during 2008 to 2021. Differences were found across racial and ethnic groups, age, mode of delivery, and comorbidities for mortality and SMM.MeaningIn this study, in-hospital maternal mortality improved between 2008 and 2021 despite increases in SMM prevalence and presence of comorbidities for the overall population.