Prenatal Exposure to Phthalates and Infant Development at 6 Months: Prospective Mothers and Children’s Environmental Health (MOCEH) Study

BACKGROUND There are increasing concerns over adverse effects of prenatal phthalate exposure on the neurodevelopment of infants. OBJECTIVES Our goal was to explore the association between prenatal di(2-ethylhexyl) phthalate and dibutyl phthalate exposure and the Mental and Psychomotor Developmental Indices (MDI and PDI, respectively) of the Bayley Scales of Infant Development at 6 months, as part of the Mothers and Children's Environmental Health Study. METHODS Between 2006 and 2009, 460 mother-infant pairs from Seoul, Cheonan, and Ulsan, Korea, participated. Prenatal mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MBP) were measured in one urine sample acquired from each mother during the third trimester of pregnancy. Associations with log-transformed creatinine-corrected phthalate concentrations were estimated using linear regression models adjusted for potential confounders. RESULTS MDI was inversely associated with the natural log concentrations (micrograms per gram creatinine) of MEHHP [β = -0.97; confidence interval (CI), -1.85 to -0.08] and MEOHP (β = -0.95; CI, -1.87 to -0.03), and PDI was inversely associated with MEHHP (β = -1.20; CI, -2.33 to -0.08). In males, MDI was inversely associated with MEHHP (β = -1.46; CI, -2.70 to -0.22), MEOHP (β = -1.57; CI, -2.87 to -0.28), and MBP (β = -0.93; CI, -1.82 to -0.05); PDI was inversely associated with MEHHP (β = -2.36; CI, -3.94 to -0.79), MEOHP (β = -2.05; CI, -3.71 to -0.39), and MBP (β = -1.25; CI, -2.40 to -0.11). No significant linear associations were observed for females. CONCLUSIONS The results suggest that prenatal exposure to phthalates may be inversely associated with the MDI and PDI of infants, particularly males, at 6 months.