HRs and 95% confidence intervals (CIs) were calculated for per interquartile range (IQR) increment for green space (NDVI); PTB, preterm birth; MPTB, moderately PTB; VPTB, very PTB.
All models adjusted for maternal age, race/ethnicity, educational level, and median household income at census block-group level; maternal address ZIP code was fitted as a random effect.