State Abortion Restrictions and Infant Mortality in the United States

Importance Restrictive abortion policies may have unintended consequences for perinatal outcomes, yet evidence on their impact on infant mortality remains limited. Objective To assess whether complete state-level abortion bans are associated with changes in neonatal and postneonatal mortality in the United States. Design Population-based serial cross-sectional study (1999–2024) using nationwide vital statistics data. Causal effects were estimated using synthetic difference-in-differences, interaction-weighted event-study models, and Bayesian hierarchical modeling. Setting and Participants All live births in the United States across all 50 states and the District of Columbia. Twelve states implementing complete abortion bans were compared with pre-ban trends and states without bans. Main Outcomes Neonatal mortality (0–27 days) and postneonatal mortality (28–364 days) per 1,000 live births. Results Complete abortion bans were associated with significant increases in neonatal mortality but not postneonatal mortality. Synthetic difference-in-differences estimates showed an increase of 0.281 neonatal deaths per 1,000 live births (95% CI, 0.128–0.430). Bayesian hierarchical models indicated increases emerging one year post-ban (0.050, 97%–3% HDI 0.006–0.090), rising at two years (0.132, 97%–3% HDI 0.089–0.178), and remaining elevated at three years (0.127, 97%–3% HDI 0.070–0.183). Event-study analyses showed increased neonatal mortality three years post-ban (0.303, 95% CI 0.033–0.573). No consistent associations were observed for postneonatal mortality. Findings were robust across multiple sensitivity analyses. Conclusions Complete state-level abortion bans were associated with sustained increases in neonatal mortality, indicating potential adverse effects of restrictive abortion policies on early-life outcomes.