Birth outcomes and background exposures to select elements, the Longitudinal Investigation of Fertility and the Environment (LIFE)

• We assessed the impact of preconception parental trace elements on birth outcomes.
• We detected more effects for paternal exposure, than for maternal exposure.
• We most consistently detected effects for preconception levels of urine W and U.

Evidence suggests that trace exposures to select elements may increase the risk for adverse birth outcomes. To investigate further, we used multiple regression to assess associations between preconception parental exposures to Pb, Cd, and total Hg in blood, and 21 elements in urine, with n=235 singleton birth outcomes, adjusted for confounders and partner's exposure. Earlier gestational age at delivery (GA) was associated with higher tertiles of urine maternal W (−1.22 days) and paternal U (−1.07 days), but GA was later for higher tertiles of maternal (+1.11 days) and paternal (+1.30 days) blood Hg. Additional analysis indicated shorter GA associated with higher paternal urine Ba, W, and U, and with higher maternal blood Pb for boys, but GA was longer in association with higher maternal urine Cr. Birth weight (BW) was lower for higher tertiles of paternal urine Cs (−237.85 g), U (−187.34 g), and Zn (−209.08 g), and for higher continuous Cr (P=0.021). In contrast, BW was higher for higher tertiles of paternal urine As (+194.71 g) and counterintuitively for maternal blood Cd (+178.52 g). Birth length (BL) was shorter for higher tertiles of urine maternal W (−1.22 cm) and paternal U (−1.10 cm). Yet, higher tertiles of maternal (+1.11 cm) and paternal (+1.30) blood Hg were associated with longer BL. Head circumference at delivery was lower for higher tertiles of paternal urine U (−0.83 cm), and for higher continuous Mo in boys (−0.57 cm). Overall, associations were most consistently indicated for GA and measures of birth size with urine W and U, and paternal exposures were more frequently associated than maternal. Though limited by several factors, ours is the largest multi-element investigation of prospective couple-level trace exposures and birth outcomes to date; the novel observations for W and U merit further investigation.