TPS 741: Adverse birth outcomes 2, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM
Background/Aim: Observational and experimental studies report associations between gestational phthalate exposure and fetal development, yet there are few data to characterize the effects on head circumference (HC) or to estimate the impact by 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.
Methods: Study participants provided up to two urine specimens during mid to late gestation, completed a study questionnaire, and allowed access to hospital birth records. Newborn anthropometrics including HC were obtained within 48 hours of delivery. We measured eight phthalate monoester metabolites (MBP, MiBP, MBzP, MEHP, MEOHP, MEHHP, MEP, and MMP) using liquid chromatography with tandem mass spectrometry, and we calculated molar sums of phthalate parent diesters (∑DEHP and ∑DBP). After specific gravity correction, we tested for associations between phthalates and neonatal HC using treatment weighted multiple informants’ linear regression, adjusted for maternal race, age, body mass index, education, smoking, and infant sex. We also explored interactions by maternal race and infant sex.
Results: HC was greater among whites than African Americans (P<0.0001) and greater for males than females (P=0.04). A doubling in urinary MEP or MMP concentration was associated with a -0.56% (95%CI: -1.03%, -0.09%) or -0.93% (95%CI: -1.70%, -0.16%) lesser HC, respectively. 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) concentrations, where associations with HC were stronger among whites than African Americans. We also detected interactions for MBP (P=0.08) and MiBP (P=0.03), where associations were stronger among females than males.
Conclusions: Our results suggest that gestational phthalate exposure is associated with diminished HC, which may reflect an impact on fetal brain development, and that whites and females have greater vulnerability.