John Meeker, Sc.D.
University of Michigan
Among a group of pregnant women in Puerto Rico, exposure to two phthalates, di-n-butyl phthalate (DBP) and di-isobutyl phthalate (DiBP), was linked to reduced gestational age at delivery and increased odds of preterm birth, according to an NIEHS-funded study.
The researchers took urine samples from 1,090 women in Puerto Rico at approximately 20, 24 and 28 weeks of pregnancy and measured for markers of different phthalate chemicals. Exposure to phthalates could occur through drinking water sources, diet, and use of consumer products.
Researchers found that higher urinary concentrations of DBP metabolites in women translated into 42% greater odds of having a preterm birth compared with women with lower exposures. Higher urinary concentrations of DiBP metabolites were associated with 32% greater odds of having a preterm birth. On average, women with DBP exposure levels in the highest 25% of the population had a pregnancy that was 1.55 days shorter than women whose exposure was in the lowest 25%. Associations were highest for urinary concentrations measured at the second study visit, near the end of the second trimester.
According to the authors, results from a limited number of other studies have been inconsistent, but this most recent work represents one of the largest and most detailed prospective cohort studies to investigate these associations to date. The authors suggest that phthalate exposures may be contributing to elevated rates of preterm birth found in Puerto Rico.
Citation: Ferguson KK, Rosen EM, Rosario Z, Feric Z, Calafat AM, McElrath TF, Velez Vega C, Cordero JF, Alshawabkeh A, Meeker JD. 2019. Environmental phthalate exposure and preterm birth in the PROTECT birth cohort. Environ Int 132:105099.