Women who are exposed to stress and plastic additives simultaneously further in their pregnancy are at an increased risk for premature birth, according to a new study by Environment International.

The third trimester is the 'critical window' for risk, according to researcher Emily Barrett, an associate professor at Rutgers School of Public Health and Environmental and Occupational Health Sciences Institute.

The study is the first to analyze the link between stress and phthalates -- a group of chemicals in plastics that makes them bendable. In other words, they are everywhere.  This agent is found in personal care products, food packaging, and electronics.  The findings are the latest in the Infant Development and the Environment Study, which tracked 783 women throughout their pregnancies between 2010 and 2012.

People are exposed to phthalates every day. The exposure to the agent is from the chemicals that food packaging and containers produce. People are exposed to the agent through touch and by oral consumption. By eating and drinking through these containers and packaging you are not just consuming the food and beverage but all the chemicals that the product was made and prepared on. With personal care and beauty products, you are inhaling and breathing in the agents and then applying it to your skin.

"Mothers who had higher levels of phthalates in their urine and reported stress during their pregnancy as well were more likely to give birth preterm," Barrett said. "We think that stress may make the body more vulnerable to the impacts of chemicals in our environment, like phthalates."

While stress itself is not related to being exposed to these plastic additives, stress can affect the immune system that can lead to inflammation and change hormone levels of pregnant women. This potentially makes these women more vulnerable to the negative effects of phthalates.

The researchers analyzed urine samples all throughout the women's pregnancies for traces of the harmful agents. They conducted questionnaires that they completed in their third trimester about stressful events such as; job loss, serious illness, family death, relationship difficulties, legal or financial problems.  About nine percent of the women delivered prematurely, 70 percent of those were spontaneous.

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Barrett noted other factors like how a woman perceives stress and how she uses her social supports to deal with stress to cope while pregnant. Barrett also noted the total number of stress events in her life and analyzed how that can affect how stress during pregnancy affects her child's health.  While it is impossible to avoid plastic additives completely, Barrett recommends that pregnant women limit their exposure to phthalates by eating less processed foods and reducing the use of plastics and personal care products.