Racial andEthnicDisparitiesinPhthalateExposureandPretermBirth: APooled Study ofSixteenUS Cohorts

BACKGROUND: Phthalate exposuresareubiquitousduringpregnancyandmaycontributetoracialandethnicdisparitiesinpretermbirth. OBJECTIVES: We investigatedraceandethnicityintherelationshipbetweenbiomarkersofphthalateexposureandpretermbirthbyexamining: a) how hypotheticalreductionsinracialandethnicdisparitiesinphthalatemetabolitesmightreducetheprobabilityofpretermbirth; and b) exposureresponse modelsstratified byraceandethnicity. METHODS: We pooledindividual-leveldataon6,045pregnanciesfrom16U.S. cohorts. Weinvestigatedcovariate-adjusteddifferences innineurinary phthalate metaboliteconcentrationsbyraceandethnicity[non-HispanicWhite(White, 43%), non-HispanicBlack(Black, 13%), Hispanic/Latina38%), andAsian/Pacific Islander(3%)]. Usingg-computation, weestimatedchangesintheprobabilityofpretermbirthunderhypotheticalinterventions toeliminatedisparitiesinlevelsofurinaryphthalatemetabolitesbyproportionallyloweringaverageconcentrationsinBlackandHispanic/ Latina participantstobeapproximatelyequaltotheaveragesinWhiteparticipants. Wealsousedraceandethnicity-stratified logisticregressionto characterize associationsbetweenphthalatemetabolitesandpretermbirth. RESULTS: In comparisonwithconcentrationsamongWhiteparticipants, adjustedmeanphthalatemetaboliteconcentrationswereconsistentlyhigher among BlackandHispanic/Latinaparticipantsby23%-148% and4%-94%, respectively. Asian/Pacific Islanderparticipantshadmetabolitelevelsthat were similartothoseofWhiteparticipants. Hypotheticalinterventionstoreducedisparitiesinmetabolitemixtureswereassociatedwithlowerprobabilities ofpretermbirthforBlack[13% relativereduction; 95% confidence interval(CI): -34%, 8.6%] andHispanic/Latina(9% relativereduction; 95% CI: -19%, 0.8%) participants. Oddsratiosforpretermbirthinassociationwithphthalatemetabolitesdemonstratedheterogeneitybyraceand ethnicity fortwoindividualmetabolites(mono-n-butyl andmonoisobutylphthalate), withpositiveassociationsthatwerelargerinmagnitudeobserved among BlackorHispanic/Latinaparticipants. CONCLUSIONS: Phthalate metaboliteconcentrationsdiffered substantiallybyraceandethnicity. Ourresultsshowhypotheticalinterventionstoreduce population-level racialandethnicdisparitiesinbiomarkersofphthalateexposurecouldpotentiallyreducetheprobabilityofpretermbirth. https://doi.