State Social Expenditures and Preterm Birth and Low Birth Weight in the US

ImportanceAdverse birth outcomes in the US, including preterm birth and low birth weight, are strongly tied to socioeconomic disadvantage and disproportionately impact infants of Black mothers. Increasing investments in social programs represents a potential policy approach to addressing disparities in birth outcomes.ObjectiveTo examine state-level associations of government expenditures on social programs with rates of preterm birth and low birth weight both overall and by race.Design, Setting, and ParticipantsThis cross-sectional, ecological study was conducted among liveborn infants in the 50 US states between January 1, 2011, and December 31, 2019. Data analysis was performed from May 2022 to May 2024.ExposuresYearly state and local government expenditures per low-income person on social programs in the following categories: state refundable Earned Income Tax Credit; cash assistance; childcare assistance; housing and community development; and public health.Main Outcomes and MeasuresYearly state-level rates of preterm birth (gestational age <37 weeks) and low birth weight (<2500 g).ResultsFrom January 1, 2011, to December 31, 2019, there were 35.1 million live births in the US, of which 3.4 million (9.8%) were preterm and 2.8 million (8.1%) were low birth weight. Median (IQR) state social expenditures per low-income person were $1546 ($1074-$2323). Greater total state social expenditures were associated with lower overall rates of preterm birth (adjusted prevalence ratio [aPR] for every increase of $1000 per low-income person, 0.99; 95% CI, 0.97-0.999) but not with overall rates of low birth weight. In secondary analyses, greater state social expenditures were associated with lower preterm birth rates for infants of Black mothers (aPR, 0.96; 95% CI, 0.92-0.999). Greater state expenditures specifically on cash assistance (aPR, 0.64; 95% CI, 0.43-0.94) and housing and community development (aPR, 0.91; 95% CI, 0.84-0.98) were associated with lower preterm birth rates for infants of Black mothers.Conclusions and RelevanceIn this cross-sectional, ecological study, greater state-level expenditures on social programs were associated with reduced rates of preterm birth, particularly for infants of Black mothers. State and local governments may consider bolstering investments in cash assistance and housing and community development to address maternal and infant health disparities.