Fig. 1

Forest plot of associations between gestational age and risk score quartiles (reference category is quartile 1). ERS/WQS was generated from the average exposure analysis and categorized into quartiles. Single-pollutant average exposure models for MECPP and MBP, where MECPP and MBP are split into quartiles, are also included. Models were adjusted for average specific gravity, maternal age at first visit, race, education, and health insurance provider. Exact numerical results can be found in Additional file 1: Table S6