Phthalates Linked to Preterm Delivery

Phthalates, a group of hormone-mimicking chemicals used to increase the flexibility of plastics, may increase a woman's risk of giving birth preterm, researchers found.

Often called plasticizers, phthalates are found in everything from vinyl flooring and adhesives to detergents, raincoats and a wide range of personal care products, including soaps, shampoos, hair sprays and nail polishes.

Once they enter the body, they are converted into metabolites, the substance that results when the body breaks down a chemical or compound. These are then passed in a person's urine.

Led by Kelly Ferguson of the University of Michigan School of Public Health, researchers analyzed the urine samples of 130 women who gave birth preterm, and 352 controls.

According to LIveScience, those women with the highest levels of phthalate metabolites were between two to five times more likely to give birth preterm when compared to those with the lowest levels.

Furthermore, in the 57 women who gave birth preterm despite not having any diagnosed medical condition, the relationship between phthalate exposure and risk of preterm delivery was even higher.

"Our results indicate a significant association between exposure to phthalates during pregnancy and preterm birth, which solidifies prior laboratory and epidemiologic evidence," the authors wrote in the study, adding that the results "provide strong support for taking action in the prevention or reduction of phthalate exposure during pregnancy."

While the study merely identifies a correlation, and not causality, the researchers say there are reasons to believe that phthalates may be to blame for a portion of the preterm births, according to Mother Nature Network. For one, phthalates may trigger inflammation in the uterine lining, they hypothesize.

"Further support for a causal relationship between prenatal phthalate exposure and spontaneous preterm delivery would come from a study that obtained biomarkers, not only of phthalate exposure, but also uterine inflammation, and showed these to be related in cases of spontaneous preterm delivery but not among those delivered preterm for a variety of medical indications," wrote Shanna Swan of the Icahn School of Mount Sinai in a related editorial.

Not involved in the study, Swan said the researchers "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."