Maternal prenatal urinary phthalate metabolite concentrations and visual recognition memory among infants at 27 weeks

Background: Prior research has demonstrated inverse associations between maternal prenatal urinary phthalate metabolite concentrations and cognitive development assessed in preschool and school-aged children. While there are a limited number of studies that evaluated these associations during infancy, no study has evaluated whether these associations exist when using the Fagan Test of Infant Intelligence (FTII), which captures novelty preference as a function of visual recognition memory. Objective: We evaluated associations between phthalate metabolite concentrations in maternal prenatal urine and cognition in infancy using the FTII at 27 weeks and determine if these associations are sex-specific. Methods: Mono-n-butyl phthalate (MnBP), monobenzyl phthalate (MBzP), monoisobutyl phthalate (MiBP), mono-ethyl phthalate (MEP), mono-3-carboxypropyl phthalate (MCPP) and four di-2-ethylhexyl phthalate metabolites (DEHP) were quantified in urine samples collected from 168 minority women living in urban neighborhoods during their third trimester of pregnancy. The FIE was administered to infants at 27 weeks to measure visual recognition memory and was recorded as the novelty preference score. Results: There were no associations between prenatal phthalate metabolite concentrations and novelty preference score in the full sample. However, there was evidence of effect modification by infant sex. Sex stratified models demonstrated that compared to girls in the lowest tertile of MBzP concentrations, girls in tertiles 2 and 3 had, on average, 3.98 and 4.65 points lower novelty preference scores (p-value=0.04 and 0.03, respectively). The relationship was similar for Sigma DEHP, MiBP, and MEP. Effects among boys were inconsistent and generally not significant. Conclusion: Maternal prenatal exposure to some phthalates was negatively associated with visual recognition memory as measured by the FTII among girls at age 27 weeks.