Placental cadmium, genetic variations, and birth size

Abstract

Background: While maternal cadmium (Cd) burden has been associated with fetal growth markers (including birth weight and head circumference), associations of placental Cd with birth size is less clear. Further, the role of genetics in these associations has not been examined. We investigated associations of placental Cd with birth size and the role of placental genotypes in this relationship. Methods: Participants were 527 mother-child pairs from the OMEGA and Placental Microarray studies. Placental Cd was measured using Agilent 7500 ICP-MS. Placental single nucleotide polymorphisms (13 SNPs) related to metal transport, growth regulation, endocrine response, and cell signaling were genotyped. Multivariable linear regression models were used to examine associations of placental Cd (quartiles) with birth weight, ponderal index and head circumference, adjusted for maternal covariates. Potential effect modification by infant sex or placental SNPs were examined using interaction terms and stratified analyses. Results: The mean maternal age and pre-pregnancy BMI were 33.7 years (SD=4.4) and 23.9 (SD=0.04) respectively. The mean Cd level in placenta was 0.0039 ng/mg tissue (SD=0.0027 ng/mg tissue). Placental Cd was not associated with birth weight (ß=7.579, 95%CI: -38.597, 53.755), ponderal index (ß=-0.015, 95%CI: -2.385, 2.355) or head circumference (ß=-0.095, 95%CI: -0.503, 0.313). SNPs were also not associated with placental Cd and interaction terms with infant sex or SNPs were not significant.Conclusions: In the current study, placental Cd was not associated with birth size or placental genotypes.