Mothers who are exposed to particulate air pollution of the type emitted by vehicles, urban heating and coal power plants are significantly more likely to bear children of low birth weight, an international study has revealed.
The study, led by co-principal investigator Tracey J. Woodruff, PhD, MPH, professor of obstetrics and gynecology and reproductive sciences at UC San Francisco along with Jennifer Parker, PhD, of the National Center for Health Statistics, Centers for Disease Control and Prevention, is the largest of its kind ever performed.
It analyzed data collected from more than three million births in nine nations at 14 sites in North America, South America, Europe, Asia and Australia.
The researchers found that at sites worldwide, the higher the pollution rate, the greater the rate of low birth weight.
Low birth weight (a weight below 2500 grams or 5.5 pounds) is associated with serious health consequences, including increased risk of postnatal morbidity and mortality and chronic health problems in later life, noted lead author Payam Dadvand, MD, PhD, of the Centre for Research in Environmental Epidemiology (CREAL) in Barcelona, Spain.
In the study, the team assessed data collected from research centres in the International Collaboration on Air Pollution and Pregnancy Outcomes, an international research collaborative established in 2007 to study the effects of pollution on pregnancy outcomes. Most of the data assessed was collected during the mid-1990s to the late 2000s, and in some cases, earlier.
"What's significant is that these are air pollution levels to which practically everyone in the world is commonly exposed. These microscopic particles, which are smaller than the width of a human hair, are in the air that we all breathe," said Woodruff.
Woodruff noted that nations with tighter regulations on particulate air pollution have lower levels of these air pollutants.
Whether these pregnancy exposures can have effects later in life, currently is under investigation through an epidemiological follow-up of some of the children included in these studies.
The study was published in the journal Environmental Health Perspectives.