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. 2019 Nov:132:105099.
doi: 10.1016/j.envint.2019.105099. Epub 2019 Aug 17.

Environmental phthalate exposure and preterm birth in the PROTECT birth cohort

Kelly K Ferguson  1 , Emma M Rosen  2 , Zaira Rosario  3 , Zlatan Feric  4 , Antonia M Calafat  5 , Thomas F McElrath  6 , Carmen Vélez Vega  3 , José F Cordero  7 , Akram Alshawabkeh  4 , John D Meeker  8
Affiliations

Environmental phthalate exposure and preterm birth in the PROTECT birth cohort

Kelly K Ferguson et al. Environ Int. 2019 Nov.

Abstract

Background: Preterm birth is a global public health issue and rates in Puerto Rico are consistently among the highest in the USA. Exposures to environmental contaminants might be a contributing factor.

Methods: In a preliminary analysis from the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) cohort (n = 1090), we investigated the association between urinary phthalate metabolite concentrations measured at three study visits (targeted at 20, 24, and 28 weeks of gestation) individually and averaged over pregnancy with gestational age at delivery and preterm birth. We additionally assessed differences in associations by study visit and among preterm births with a spontaneous delivery.

Results: Compared to women in the general USA population, urinary concentrations of metabolites of di-n-butyl phthalate (DBP) and di-isobutyl phthalate (DiBP) were higher among pregnant women in Puerto Rico. Interquartile range (IQR) increases in pregnancy-averages of urinary metabolites of DBP and DiBP were associated with shorter duration of gestation and increased odds of preterm birth. An IQR increase in mono-n-butyl phthalate (MBP), a metabolite of DBP, was associated with 1.55 days shorter gestation (95% confidence interval [CI] = -2.68, -0.42) and an odds ratio (OR) of 1.42 (95% confidence interval [CI]: 1.07, 1.88) for preterm birth. An IQR increase in mono-isobutyl phthalate (MiBP), a metabolite of DiBP, was associated with 1.16 days shorter gestation (95% CI = -2.25, -0.08) and an OR of 1.32 (95% CI: 1.02, 1.71) for preterm birth. Associations were greatest in magnitude for urinary concentrations measured at the second study visit (median 23 weeks gestation). DiBP metabolite associations were greatest in magnitude in models of spontaneous preterm birth. No associations were detected with other phthalate metabolites, including those of di-2-ethylhexyl phthalate.

Conclusion: Among pregnant women in the PROTECT cohort, DBP and DiBP metabolites were associated with increased odds of preterm birth. These exposures may be contributing to elevated rates of preterm birth observed in Puerto Rico.

Keywords: Gestational age; Phthalates; Preterm birth; Puerto Rico; Superfund.

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Conflict of interest statement

Conflict of interest statement: The authors declare that they have no actual or potential conflicts of interest.

Figures

Figure 1.
Figure 1.
Adjusteda odds ratios (95% confidence intervals) between an interquartile range difference in urinary phthalate or phthalate alternative metabolite concentrations by study visit and preterm birth. aAdjusted for maternal age (continuous), education (4 level ordinal variable), urinary specific gravity, and gestational age at sample collection.
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