Several studies conducted in Los Angeles and New York City have identified high concentrations of air pollution as harmful to a developing fetus, but there have been few studies of traffic-related air pollution and birth outcomes in areas that have low to moderate air pollution.  Now, a team led by Sheela Sathyanarayana, MD, MPH, of Seattle Children’s Research Institute, has found modest effects on fetal growth in the Puget Sound Air Basin, a region in Washington state with low overall air pollutant concentrations.

Traffic in Seattle

The study is the first in the United States to examine low level traffic-derived air pollutants in relation to small for gestational age birth, and was published in Air Quality, Atmosphere & Health.

“We found associations in the Puget Sound area between increased levels of nitrogen dioxide exposures and an increased risk of small for gestational age birth,” said Dr. Sathyanarayana.  Small for gestational age babies are smaller in size than normal for the baby’s sex and for the number of weeks of pregnancy.  It is not the same as a low birth weight baby.

Nitrogen dioxide refers to traffic and industrial pollution and is the criteria used in regulating air pollutants. 

Dr. Sathyanarayana and the research team also found associations between living within 50 to 150 meters of freeways and highways and an increased risk of small for gestational age birth.  “The closer you live to a major highway or roadway, the larger the risk is for having a small for gestational age birth baby,” she said.

Parents or women considering a pregnancy should be aware that air pollution can affect health outcomes, based on the research.  The study findings are also a call-to-action for regulatory agencies.  “Current regulations may not be protecting patients from the risk of small for gestational age birth,” said Dr. Sathyanarayana.

Babies with small for gestational age birth may have problems at birth including decreased oxygen levels, hypoglycemia (low blood sugar) and difficulty maintaining normal body temperature.  Up to 90 percent of babies born with small for gestational age birth catch up in growth by the age of two.

If you’d like to arrange an interview with Dr. Sathyanarayana, please contact Children’s PR team at 206-987-4500 or at press@seattlechildrens.org

Dr. Sathyanarayana is an assistant professor of Pediatrics at the University of Washington. Co-authors on the study include Chuan Zhou (Seattle Children’s Research Institute); Carole Rudra (University at Buffalo/ The State University of New York); and Tim Gould, Tim Larson, Jane Koenig and Catherine Karr (University of Washington).