Maternal Exposure to DDT and Pyrethroids and Birth Outcomes Among Residents of an Area Sprayed for Malaria Control Participating in the VHEMBE Birth Cohort Study

Abstract

Although effective in controlling malaria, Indoor Residual Spraying results in elevated exposure to insecticides such as dichlorodiphenyltrichloroethane (DDT) and pyrethroids. These chemicals cross the placenta but no studies have examined their associations with birth outcomes in populations residing in indoor residual spraying areas. We investigated this question in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), a birth cohort study of 751 South African children born between 2012 and 2013. We measured maternal peripartum serum DDT and urine pyrethroid metabolite concentrations and collected data on birth weight, length, head circumference and gestational duration. We analyzed data using marginal structural models with inverse probability of treatment weights, generalized propensity scores and standard conditional linear regression. p,p'-DDT, o,p'-DDT and, to a lesser extent, p,p'-dichlorodiphenyldichloroethylene were related to elevated birth weight, length and head circumference among girls only, using all three analytical methods. Changes in gestational duration did not mediate this relation, suggesting exposures accelerate fetal growth, which is consistent with the known estrogenic properties of o,p'-DDT and p,p'-DDT. No associations were found with pyrethroid metabolites. Results suggest prenatal exposure to DDT is related to elevated birth size. Further studies are needed to elucidate the implications of these findings.