Background: Research suggests prenatal phthalate exposures affect child executive function and behavior.
Objectives: To evaluate associations between phthalate metabolite concentrations in maternal prenatal urine and mental, motor and behavioral development in children at age 3 years.
Methods: Mono-n-butyl phthalate (MnBP), mono-benzyl phthalate (MBzP), mono-isobutyl phthalate (MiBP) and 4 di-2-ethylhexyl phthalate metabolites were measured in a spot urine sample collected from 319 women during the 3rd trimester. At child age 3 years, the Mental Development Index (MDI) and Psychomotor Development Index (PDI) were measured using the Bayley Scales of Infant Development II, and behavior problems were assessed by maternal report on the Child Behavior Checklist.
Results: Child PDI scores decreased with increasing logeMnBP (estimated adjusted coefficient [β]= -2.81 [95% confidence interval (CI) -4.63, -1.0]) and logeMiBP (β= -2.28 [95% CI -3.90, -0.67]); odds of motor delay increased significantly (estimated adjusted odds ratios (OR)=1.64 [95%CI 1.10, 2.44] and 1.82 [95% CI 1.24, 2.66 per logeMnBP and logeMiBP). In girls, MDI scores decreased with increasing logeMnBP (β= -2.67 `[95% CI -4.70, -0.65]); the child sex difference in odds of mental delay was significant (p=0.037). The OR for clinically withdrawn behavior were 2.23 (95% CI 1.27, 3.92) and 1.57 (95% CI 1.07, 2.31) per loge unit increase in MnBP and MBzP, respectively; for clinically internalizing behaviors, the OR was 1.43 (95% 1.01, 1.90) per loge unit increase in MBzP. Significant child sex differences were seen in associations between MnBP and MBzP and behaviors in internalizing domains (p<0.05).
Conclusion: Certain prenatal phthalate exposures may decrease child mental and motor development and increase internalizing behaviors.