Early pregnancy exposure to metals and maternal depressive symptom trajectories in Project Viva

Abstract

BACKGROUND AND AIM: Exposure to neurotoxicant metals, hypothesized to alter dopaminergic function, have not been sufficiently explored as a risk factor for maternal depression. We evaluated the extent to which early pregnancy blood levels of essential and non-essential metals were prospectively associated with depressive symptom trajectories from mid-pregnancy to 7-years postpartum. METHODS: Participants were 872 women in Project Viva, a longitudinal Boston-area cohort recruited during pregnancy (1999-2002). We measured levels of 11 metal(loid)s (arsenic, barium, cadmium, cesium, copper, mercury, magnesium, manganese, lead, selenium, zinc) in maternal first trimester erythrocytes. We assessed depressive symptoms via the Edinburgh Postnatal Depression Scale at mid-pregnancy and four postpartum timepoints (6 months, 1, 3, 7 years). Utilizing latent class mixed modeling, we identified three depressive symptom trajectories: stable low (86%); elevated perinatal symptoms, then decreasing (9%); and moderate perinatal symptoms, then increasing (5%), among women with ≥3 repeat measures. Adjusting for maternal sociodemographics and dietary intake, we used multinomial logistic regression to test associations of individual metal levels with odds of having an increasing or decreasing trajectory. RESULTS:In our cohort of moderately high socioeconomic status participants (e.g., 75% college graduate), correlations between metal levels were mostly positive (Spearman: 0.01-0.60), except for negative correlations between barium and all other elements. Compared to having a stable low trajectory, a doubling of blood arsenic was associated with 1.27 (95% confidence interval: 1.01, 1.59) odds of an increasing depressive trajectory. Greater prenatal mercury blood level was associated with lower odds of having a decreasing trajectory [0.88 (95% confidence interval: 0.77, 1.00)]. All other first trimester metal levels were not associated with depressive symptom trajectory. CONCLUSIONS:In our study investigating associations of several early pregnancy metals with maternal depressive symptom trajectories, we did not observe strong evidence of associations. Residual confounding or multiple testing may explain observed associations with arsenic and mercury. KEYWORDS: Mental health outcomes, heavy metals, chemical exposures, female