Pregnant women who are exposed to phthalates – chemicals found in contaminated food and water, some deodorants, lotions and perfumes – are at increased risk of preterm birth, compared with pregnant women who are not exposed to these chemicals. This is according to a study published in the journal JAMA Pediatrics.

Phthalates are a group of chemicals commonly used in plastics to make the material more durable. They are also used as solvents for other materials and can be found in hundreds of beauty products, including soaps, shampoos, hairsprays and nail polishes.

Previous research has linked women’s exposure to phthalates to disrupted hormone levels, endometriosis and breast cancer, according to the researchers from the University of Michigan School of Public Health.

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A new study suggests that pregnant women exposed to phthalates – chemicals commonly found in some lotions, deodorants and perfumes – may be at increased risk of preterm birth.

But they note that the effects of environmental exposures on preterm birth is a subject that has not been well-studied.

In order to determine whether there is a link between pregnant women’s exposure to phthalates and preterm birth, the investigators analyzed 482 women who were recruited for the study between 2006 and 2008. Of these, 130 had experienced a preterm birth, while 352 women were used as controls.

The researchers analyzed the women’s demographic data, biological samples and information on birth outcomes. They also assessed the women’s urine samples, which were taken up to three points throughout pregnancy, to determine phthalate metabolite concentrations.

The study revealed that there was an association between high phthalate metabolite concentrations in some women’s urine during pregnancy and an increased risk of preterm birth (defined as fewer than 37 weeks’ gestation).

Explaining the importance of their findings, the researchers say:

Our results indicate a significant association between exposure to phthalates during pregnancy and preterm birth, which solidifies prior laboratory and epidemiologic evidence.

These data provide strong support for taking action in the prevention or reduction of phthalate exposure during pregnancy.”

The researchers point out that since exposure to phthalates is widespread, and because the prevalence of preterm birth among women in their study cohort was similar to that in the general population, their results are generalizable to women in the US and other countries.

In an editorial linked to the study, Shanna H. Swan, of the Icahn School of Medicine at Mount Sinai in New York, says that the investigators of this study have “elegantly presented the rationale” for further studies investigating the link between phthalate exposure and spontaneous preterm delivery.

“Moreover,” Swan adds, “they have contributed the first robust study suggesting that phthalates, pervasive in the environment of prenatal women, may be important contributors to the unknown and other causes of preterm delivery.”

The number of preterm births in the US has dropped to its lowest rate in 15 years, according to a March of Dimes report recently detailed in Medical News Today.