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Association between Gestational Phthalate Exposure and Newborn Head Circumference; Impacts by Race and Sex



Michael S. Bloom, E. Valachovic, Thoin Begum, Rebecca J. Wineland, Abby G. Wenzel, John W. Brock, Elizabeth R. Unal, Lori Cruze, Roger B. Newman, John Kucklick


Abstract Observational and experimental studies report associations between gestational phthalate exposure and fetal development, yet few data exist to characterize phthalate effects on head circumference (HC) or to estimate the impact of race or sex. To address this data gap, we enrolled 152 African American and 158 white mothers with uncomplicated singleton pregnancies from the Charleston, South Carolina (USA) metropolitan area in a prospective birth cohort. Study participants provided up to two urine specimens during mid to late gestation, completed a study questionnaire, and allowed access to hospital birth records. We measured eight phthalate monoester metabolites (MBP, MiBP, MBzP, MEHP, MEOHP, MEHHP, MEP, and MMP ) using liquid chromatography with tandem mass spectrometry, and calculated molar sums of phthalate parent diesters (∑DEHP and ∑DBP). After specific gravity correction, we tested for associations between phthalates and neonatal HC and cephalization index using weighted multiple informants linear regression, adjusted for maternal race, age, body mass index, education, smoking, and infant sex. We explored interactions by maternal race and infant sex. HC was larger for whites than African American newborns (p<0.0001) and for males than females (p=0.04). A doubling in urinary MEP concentration was associated with a -0.56% (95%CI: -1.03%, -0.09%) smaller head circumference. There were no statistically significant associations for cephalization index. We detected interactions for maternal race with urinary MBP (p=0.04), MBzP (p=0.01), MEHP (p=0.02), MMP (p=0.06), and ∑DBP (p=0.07), in which reduced HC circumference associations were stronger among whites than African Americans, and interactions for MBP (p=0.02) and MiBP (p=0.02), in which associations were stronger for females than males. Our results suggest that gestational phthalate exposure is associated with smaller neonatal HC and that white mothers and female newborns have greater vulnerability.
Environmental Research


phthalate, race, metabolite, exposure


Bloom, M. , Valachovic, E. , Begum, T. , Wineland, R. , Wenzel, A. , Brock, J. , Unal, E. , Cruze, L. , Newman, R. and Kucklick, J. (2021), Association between Gestational Phthalate Exposure and Newborn Head Circumference; Impacts by Race and Sex, Environmental Research, [online], (Accessed April 19, 2024)
Created January 29, 2021, Updated August 15, 2022