Pregnant women who are exposed to chemicals known as phthalates found in plastics, lotions and food packaging may face higher odds of giving birth prematurely, a US study said Monday.
The findings are important because prematurity is a leading cause of infant death around the world, said the report in the Journal of the American Medical Association.
"Our results indicate a significant association between exposure to phthalates during pregnancy and preterm birth," said the study led by Kelly Ferguson of the University of Michigan School of Public Health.
"These data provide strong support for taking action in the prevention or reduction of phthalate exposure during pregnancy."
The study was carried out at Brigham and Women's Hospital in Boston, Massachusetts.
A total of 130 women who gave birth before full term took part, along with 352 control participants.
Researchers analyzed the women's urine samples at different times throughout their pregnancies for levels of phthalate metabolites.
They found that the preterm cases showed "significantly elevated levels" of certain phthalates, including di-2-ethylhexyl phthalate (DEHP), mono-(2-ethyl)-hexyl phthalate (MEHP) and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP).
The higher the exposure, the more likely it was that the women would give birth too early.
For example, among the women whose concentration of the phthalate metabolite mono-(2-ethyl-5-carboxypentyl) phthalate was above the 75th percentile, the odds ratio for spontaneous preterm birth was 5.23, compared to 2.39 among all preterm births.
Phthalates are commonly found in perfumes, hair spray, nail polish, deodorants, and body lotions.
They are also used in packaging, plastic toys, vinyl, medical supplies and pharmaceuticals.
An accompanying editorial in JAMA by Shanna Swan of Mount Sinai hospital in New York said the research makes an "important public health contribution by demonstrating a sizable impact of phthalates, a class of commonly used chemicals, on a health outcome of major public health concern."
More research is needed to find out if phthalates may be causing the problem by increasing inflammation of the uterus, she wrote.
Some 15 million babies around the world are born preterm, or before 37 weeks in the womb.
