Fig. 3: Relationship among marriage age, metal exposure, and risk of preterm birth.

Relationship among marriage age, metal exposure, and risk of preterm birth in the first (A) and second trimesters (B). The yellow line indicates that the FDR is <0.05 and is positive, the blue line indicates that the FDR is <0.05 and is negative, and the gray line indicates that the FDR is larger than 0.05. C OR and 95% CI represent the indirect effects of marriage age on risk of preterm mediated through metal elements; the effects of marriage age on preterm birth were mediated by maternal serum.