John D. Meeker, Sc.D.
University of Michigan
NIEHS Grants R01ES018872, P42ES017198, P30ES017885
NIEHS-supported research has found that, depending on the phthalate examined, women with the highest levels of exposure during pregnancy had two-to-five times the odds of preterm birth, compared to women with the lowest exposure. The findings point to phthalate exposure as a potential preventable contributing factor to premature birth.
Using a nested case control study design, the researchers examined associations between average levels of phthalate exposure during pregnancy in 130 mothers who had delivered prior to 37 weeks of completed gestation. The study also included 352 control mothers who delivered at or after 37 weeks. To determine overall phthalate exposure, the researchers used multiple urine samples during pregnancy. They found that preterm birth showed the strongest dose-dependent associations with maternal levels of the di-2-ethylhexyl phthalate (DEHP) metabolites mono-(2-ethyl)-hexyl phthalate (MEHP) and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) and the summed levels of all the DEHP metabolites.
The researchers also analyzed a subset of 57 mothers with preterm deliveries proceeded by spontaneous preterm labor or preterm premature rupture of the membranes. When this group was examined alone, the odds ratios increased for all the phthalate metabolites. This finding indicates a stronger association between phthalate exposure and spontaneous preterm birth than the association with all preterm births.
Phthalate exposure can occur from food, plastics, and personal care products such as deodorants and lotions. The researchers caution that before implementing interventions aimed at decreasing phthalate exposure, more studies are needed to confirm these findings, to examine the sources of the phthalates, and to better understand the mechanisms involved.
Citation: Ferguson KK, McElrath TF, Meeker JD. 2013. Environmental phthalate exposure and preterm birth. JAMA Pediatr; doi:10.1001/jamapediatrics.2013.3699 [Online 18 November 2013].