Abstract
BACKGROUND: The United States maternal mortality rate increased after 2018, with a marked increase in 2021 followed by a decline in 2022 and 2023. Trends at the state level have not yet been examined, likely due to the small numbers of maternal deaths occurring annually in most states. Small area estimation models can provide more reliable estimates of maternal mortality at the state level, by borrowing strength over time and across geographic areas. OBJECTIVE: To examine state-level trends in maternal mortality rates from 2018 through 2023 and the contribution of COVID-19-related maternal deaths to the trends. STUDY DESIGN: Serial cross-sectional study of state-level mortality and natality data from the United States National Vital Statistics System from 2018 through 2023. Maternal deaths, defined as deaths occurring during or within 42 days of termination of pregnancy (n=4964), and live births (n=22,080,966). Hierarchical Bayesian models with spatiotemporal random effects were used to estimate smoothed maternal mortality rates (maternal deaths per 100,000 live births) and the percentage of maternal deaths involving COVID-19 by state of residence from 2018 to 2023. RESULTS: Maternal mortality rates showed consistent temporal patterns across states, peaking in 2021 and declining in 2022 to 2023. However, there was variation in magnitude, with rates 4.6 times larger in Tennessee than in California in 2021. COVID-19 accounted for the observed increases across nearly all states; maternal mortality rates excluding COVID-19 deaths were stable across most states. CONCLUSION: Findings show the impact of the COVID-19 pandemic on trends in maternal mortality rates by state, with maternal deaths involving COVID-19 nearly entirely accounting for the increases seen in maternal mortality in 2020 and 2021. Findings can inform efforts to prevent maternal deaths where rates are highest and highlight areas where maternal mortality rates are low or declining for further examination of factors that may be related to these lower rates.