Fig. 4. Subgroup-specific OR (95% CI) estimates of LBW and TLBW associated with a 0.1-unit increase in NDVI and EVI within a 3000-m buffer.

These estimates are derived from the fully adjusted model, where covariates include maternal demographic characteristics, fetal variables, and environmental factors. Error bars represent 95% confidence intervals. Effect heterogeneity between subgroups is examined through a fixed effect meta-regression method, and the statistical tests are two-sided. The exact sample sizes for subgroups are exhibited in Table 1. *** indicates P < 0.001 for effect heterogeneity between subgroups. OR odds ratio, CI confidence interval, LBW low birth weight, TLBW term low birth weight, NDVI normalized difference vegetation index, EVI enhanced vegetation index.