New research suggests women who were exposed to a group of chemicals called phthalates were more likely to give birth preterm.
The most common way for people to be exposed to the harmful chemicals is by eating food that comes in a container containing phthalates, the Centers for Disease Control and Prevention reported. They can also be found in "adhesives, vinyl flooring, plastic shower curtains, some medications and more," a University of Michigan news release reported.
"We know that exposure to phthalates is virtually ubiquitous in today's world. Rates of preterm birth are significantly higher now than they were several decades ago for unexplained reasons. In experiments with animals there have been studies showing phthalates may cause biological responses that may be relevant to preterm birth. The combination of these three things led to the hypothesis we studied here," Principle investigator John Meeker, associate professor of environmental health sciences and associate dean for research at the U-M School of Public Health, told Headlines and Global News in an email.
Meeker's research team found that women who had the highest rates of phthalate exposure were two-to-five times more likely to deliver preterm than those who had the lowest exposure rates.
The researchers warned more studies would need to be conducted in order to fully establish the link between phthalates and preterm birth.
"This is by no means the cause of premature birth, but it is a possible contributor- which is important because it is potentially modifiable," Doctor Thomas McElrath, a physician-scientist and key co-investigator on the study said. "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."
The researchers looked at 482 pregnant women and analyzed urine samples that revealed their Phthalate levels. About 130 of the women who fell into the highest phthalate level range gave birth preterm.
"Preterm birth is a major public health challenge. 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," Meeker said in the news release. "Next, we need to look at how pregnant women are exposed, and at what stage of pregnancy, to help inform exposure and risk prevention strategies."
The researchers are unsure exactly what causes the connection.
"We have some ideas on how phthalates could cause preterm birth, although the exact mechanism is still unknown," Kelly Ferguson, doctoral student at the U-M School of Public Health and first author of the paper, said. "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."
The researchers are planning to continue their studies on the link between the chemicals and preterm birth. Phthalates are suspected of causing a number of health issues.
"Other research has shown adverse effects on male reproductive development, reduced testosterone levels in men, altered thyroid function in men and women, adverse effects on child neurodevelopment, and possibly increased risk of metabolic syndrome, diabetes, obesity, and other conditions," Meeker told HNGN.
