Prenatal Metals Exposure and Child Birth and Growth in Bangladesh

Abstract

The objective of this dissertation is to contribute to ongoing research on prenatal metals exposure, in terms of arsenic, lead, and manganese, and infant health and growth, and to deepen the understanding of the complexity of such problems. We seek to do so in three parts. First we examine the association between combined prenatal metals exposure and infant birth weight and head circumference. Then, we look at the effect on birth weight from the HFE gene variants and its interaction effects with arsenic. Finally, we look at the association of prenatal metals exposure and child growth up to 36 months. The study populations of all three of our studies are taken from mothers enrolled in 2 hospitals affiliated with Dhaka Community Hospital in Bangladesh. They were given self-administered questionnaires at time of enrollment and are followed after birth. Child measurements were taken at time of birth, and the biomarker for these studies are cord blood metal measurements. In the first part of this dissertation, through multivariate linear regression, including a metal interaction term, we found that prenatal arsenic and manganese exposure individually associated with lowered birth weight and birth head circumference. We also found evidence of interactions between the two metals, suggesting that joint exposure creates greater deficit in birth outcomes. In the next part, looking at gene-environment interactions, we found significant modification effects of multiple SNPs on the HFE gene that increased the association between arsenic and birth weight. We also found direct effect of less studied HFE genes to lower birth weight. Finally, we assessed the effect of prenatal metals exposure on early growth in children through longitudinal analysis. In following the weight and height of the child from birth up to 36 months of age, our results indicated adverse association between arsenic and manganese on growth.