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Study looks at preterm births, phthalate levels

By: Jeremy Carroll

November 21, 2013

Mothers who give birth preterm have higher levels of phthalates than those who give birth at full-term, according to an association study conducted by University of Michigan researchers.

The study looked at 130 preterm births and 352 randomly assigned control participants at Brigham and Women’s Hospital in Boston, but the American Chemistry Council said a much more detailed study is needed before any conclusions could be drawn.

According to the study, women with the highest levels of exposure of certain phthalates during pregnancy had two-to-five times the odds of preterm birth, compared to women with the lowest exposure. The study took urine samples of the women at various times during their pregnancy.

The results of the study were published in the Journal of the American Medical Association Pediatrics, a monthly peer-reviewed journal.

Researchers, as well as ACC, warned that the results still need to be confirmed with more study.

“This is by no means the cause of premature birth, but it is a possible contributor — which is important because it is potentially modifiable,” said Dr. Thomas McElrath in a statement. McElrath was a co-investigator on the study.

“This finding may be dramatic but women should not be alarmed,” McElrath said. “This is only the first step in a long research process that will be needed to clarify and confirm these results. It is simply too early to suggest making changes in prenatal care based on this study.”

In a statement about the results, ACC said the study was limited to a small demographic area and it “should not be used to claim any cause-and-effect relationship between levels of phthalate DEHP exposures and the chance of preterm birth.”

ACC called phthalates one of the most widely studied family of chemicals in use today and exposure from all sources combined is extremely low.

“On review of this article, the study leaves out certain very important and widely-accepted preterm risk factors, including: poor nutrition, infections, gestational diabetes, chronic conditions such as high blood pressure and diabetes, multiple miscarriages or terminated pregnancies and stress,” ACC said in its statement. “A much more detailed review of this study would need to be conducted before any wide-spread conclusions can be drawn about any direct connection between phthalates in the environment and preterm delivery.”

Researchers said before any sort of interventions could be taken for pregnant women, more must be known about how phthalates interact with pregnancy.

“Preterm birth is a major public health challenge,” said John Meeker, associate professor of environmental health sciences and associate dean for research at the University of Michigan School of Public Health, and the principal investigator of the study. “Rates are significantly higher than they were 20 years ago and we don’t know why. Other interventions have had limited effectiveness, and this helps shed light on a potential for environmental influences.”

Phthalates are used in a number of products to make plastics more flexible. They can also be used as solvents in some personal care products.