| Prenatal exposure to depression and mercury have been independently linked to adverse infant outcomes. Though results specific to birth size remain inconsistent, they are generally associated with smaller infant anthropometrics. Increasingly, research has shifted towards examining co-occurring, cross-disciplinary exposures, and thus more studies are examining if and how psychosocial and environmental exposures jointly contribute to health. This study examines the independent effects of prenatal depression and mercury exposures on infant birth size, and also whether these exposures jointly contribute to adverse infant birth size outcomes. This study uses data from the Albany Infant and Mother Study (AIMS), an ongoing birth cohort of pregnant women and their infants (n = 148). Women completed the Edinburg Postnatal Depression Scale (EPDS), as well as provided a toenail sample for mercury analysis around 27 weeks gestation. Infant anthropometric measurements were completed at delivery; birth weight, head circumference, and a cephalization index (a ratio of head size to body weight that can indicate asymmetric intrauterine growth restriction) were considered as outcomes. Multivariable linear regression models were used to evaluate the independent and interactive effects of depression and mercury exposures in relation to birth size outcomes adjusted for relevant confounders. Neither prenatal depression nor mercury were independently associated with birthweight, head circumference, or cephalization index. Significant interactions were found for birthweight (beta = 13.40, SE = 5.88, p = 0.02) and cephalization index (beta = --0.003, SE = 0.002, p = 0.05), whereby women with prenatal depression and higher mercury exposure had infants with heavier birthweights and less cephalization (e.g. less restricted fetal growth). These results suggest that prenatal depression and mercury may jointly contribute to infant birth size outcomes. |
