Fig. 1
From: Toxic metal mixtures in private well water and increased risk for preterm birth in North Carolina
Forest plots of aORs for PTB based on tract-level metal concentrations in private wells. Models were fit comparing individuals in tracts with low (mean tract-level metal concentration =  < 50th percentile of state-wide metal concentration), medium (mean tract-level metal concentration > 50th and < 90th percentile of state-wide metal concentration) and high (mean tract-level metal concentration >  = 90th percentile of state-wide metal concentration). Models were adjusted for smoking, age, race/ethnicity, education, season of conception, tract-level poverty, tract-level nitrates and nitrites