Association of smoke-free laws with preterm or low birth weight deliveries—A multistate analysis

Objective: To assess the association between the change in statewide smoke-free laws and the rate of preterm or low birth weight delivery hospitalizations. Data Source: 2002-2013 Healthcare Cost and Utilization Project State Inpatient Databases. Study Design: Quasi-experimental difference-in-differences design. We used multivariate logistic models to estimate the association between the change in state smoke-free laws and preterm or low birth weight delivery hospitalizations. The analyses were also stratified by maternal race/ethnicity to examine the differential effects by racial/ethnic groups. Data Collection/Extraction Methods: Delivery hospitalizations among women aged 15-49 years were extracted using the International Classification of Diseases, Ninth Revision, and Diagnosis-Related Group codes. Principal Findings: Non-Hispanic black mothers had a higher rate of preterm or low birth weight delivery hospitalization than other racial/ethnic groups. Overall, there was no association between the change in smoke-free laws and preterm or low birth weight delivery rate. Among non-Hispanic black mothers, the change in statewide smoke-free laws was associated with a 0.9-1.9 percentage point (P <.05) reduction in preterm or low birth weight delivery rate beginning in the third year after the laws took effect. There was no association among non-Hispanic white mothers. A decline in the black-white disparity of 0.6-1.6 percentage points (P <.05) in preterm or low birth weight delivery rates was associated with the change in state smoke-free laws. Conclusion: The change in state smoke-free laws was associated with a reduction in racial/ethnic disparities in preterm or low birth weight delivery hospitalizations in selected US states.