Preterm Birth and Exposure to Environmental Pollutants

By Roberta Attanasio

“Being born too soon is an unrecognized killer” – these are the words of Professor Joy Lawn, Director of the MARCH Centre at the London School of Hygiene and Tropical Medicine and a Senior Health Advisor to Save the Children. Professor Lawn is one of the co-editors of a 2012 seminal report entitled “Born too soon: the global action report on preterm birth.”

Globally, more than 15 million babies are born prematurely (before 37 completed weeks of gestation) each year, with over a million neonatal deaths from complications of preterm birth. To reduce the global staggering numbers of preterm births, it is necessary to find ways to help all pregnancies go to full term, or 39 weeks. “Prevention will be the key”, said Elizabeth Mason, M.D., Director of Maternal, Newborn, Child and Adolescent Health at the World Health Organization and a major contributor to the report, “We are now looking closely at what can be done before a woman gets pregnant to help her have an optimal outcome.”

Strong research programs are needed to clearly identify and understand the large variety of risk factors associated with preterm births, so that appropriate action can be taken to limit the number of  ”born too soon” babies.

What are some of the potential risk factors? Could exposure to environmental pollutants be one of them? This is certainly an understudied factor. Now, a new study published online on November 18, 2013,  in the Journal of the American Medical Association (JAMA) Pediatrics and entitled “Environmental Phthalate Exposure and Preterm Birth” concludes that “Women exposed to phthalates during pregnancy have significantly increased odds of delivering preterm. Steps should be taken to decrease maternal exposure to phthalates during pregnancy.”

According to a fact sheet published by the Centers for Disease Control and Prevention (CDC), “Phthalates are a group of chemicals used to make plastics more flexible and harder to break. They are often called plasticizers. Some phthalates are used as solvents (dissolving agents) for other materials. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, plastic clothes (raincoats), and personal-care products (soaps, shampoos, hair sprays, and nail polishes).”

People, including pregnant women, are exposed to phthalates worldwide. The CDC fact sheet states that “by measuring phthalate metabolites in urine, scientists can estimate the amount of phthalates that have entered people’s bodies.” Using this method, CDC researchers found that phthalate exposure is widespread in the U.S. population and that adult women have higher levels of urinary metabolites than men for those phthalates that are used in soaps, body washes, shampoos, cosmetics, and similar personal care products.”

The JAMA Pediatrics study included 482 individuals selected from a larger population of pregnant women who delivered at the Brigham and Women’s Hospital in Boston from 2006 to 2008. Phthalate levels were measured in urine samples taken from up to three time points during pregnancy from each woman. The 130 mothers who delivered prior to 37 weeks had significantly higher concentrations of phthalate metabolites in their urine.

Dr. Thomas McElrath, one of the researchers involved in the study, said “This is by no means the cause of premature birth, but it is a possible contributor— which is important because it is potentially modifiable. This finding may be dramatic but women should not be alarmed. 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.”

Kelly Ferguson, first author of the paper, added “We have some ideas on how phthalates could cause preterm birth, although the exact mechanism is still unknown. One possibility we are considering is that phthalates are causing changes in oxidative stress or inflammation in the mother, and that these changes are leading to early labor.”

Will results from this and future studies address, at least in part, the global toll of preterm birth?

Addressing preterm birth is an urgent priority for reaching the United Nations Millennium Development Goal 4, which calls for the reduction of child deaths by two-thirds between 1990 and 2015.