Background Widespread phthalate exposure has prompted investigations concerning their potential adverse health effects. The objective of this study was to evaluate the impact of pre and early postnatal phthalate exposure on child psychomotor development basing on the data from the prospective Polish Mother and Child Cohort Study (REPRO PL).

Methods Phthalate exposure was determined by measuring 11 phthalate metabolites (MEP, MiBP, MnBP, 3OH-MnBP, MBzP, MEHP, 5OH-MEHP, 5oxo-MEHP, 7OH-MiNP, 7oxo-MiNP, MnOP) in the urine collected from mothers during the third trimester of pregnancy (prenatal exposure) and from their children at 24 th month of age (postnatal exposure). The analysis was performed by HPLC-MS/MS method. Child psychomotor development was assessed at the 2 nd year of age by Bayley Scales of Infant and Toddler Development.

Results Child motor development was inversely associated with natural log concentrations (µg/g creatinine) of 3OH-MnBP (β=-2.3; 95% CI -4.0 to -0.6), 5OH-MEHP (β=-1.2; 95% CI -2.2 to -0.3), 5oxo-MEHP (β=-1.8; 95% CI -330 to -0.2) and DEHP metabolites (β=-2.2; 95% CI -3.60 to -0.8) and sum of high molecular weight phthalates (β=-2.5; 95% CI -4.1 to -0.9) in the urine collected from mothers during pregnancy after adjustment for variety of potential confounders. Additional adjustment for postnatal phthalate exposure did not change the results. Postnatal child exposure to phthalates was not associated with any of the measured scores of child psychomotor development.

Conclusions The study findings add further support to the possibility that prenatal phthalate exposure may be detrimental to child neurodevelopment and underscore the importance of policies and public health interventions to reduce such exposure.