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. Author manuscript; available in PMC: 2021 May 1.
Published in final edited form as: Environ Int. 2020 Mar 13;138:105606. doi: 10.1016/j.envint.2020.105606

Figure 2.

Figure 2.

Preterm birth (overall) odds ratio (95% confidence interval) associated with tertiles of geometric average exposureab Models were adjusted for maternal age, maternal education, pre-pregnancy BMI, and exposure to secondhand smoking.

a Referent levels were set at tertile 2 for essential metals (Cu, Mn, Zn).

b Referent levels were set at tertile 1 for non-essential metals (Hg, Pb), and environmental risk score (ERS). Δ Individual metals that were selected from elastic net models to compose ERS.