From Smog to Small Babies

Air pollution linked to babies with low birth weight

February 9, 2013 / Author:  / Reviewed by: Chris Galloway, M.D.

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(dailyRx News) In hopes of having a healthy baby, most women try to make good choices during their pregnancies. Some choices, like which foods to eat and what exercise to do, are easy to make. But they can't always choose the air they breathe.

A recent study showed a link between the amount of air pollution a woman is exposed to during her pregnancy and the chances that she’ll have a baby with low birth weight.

Researchers studied the records of over three million births all over the world. They examined air pollution levels during the entire duration of the pregnancies and babies' birth weights for each pregnancy.

Women who were exposed to the highest rates of air pollution during their pregnancies had the highest rates of low birth weight babies.

Low birth weight is associated with health problems later in life for the infant.

"Avoid polluted areas during pregnancy."

Payam Dadvand, MD, of the Centre for Research in Environmental Epidemiology in Barcelona, Spain, and colleagues set out to study the relationship between pregnant women's exposure to air pollution and the birth weight of their babies.

To carry out their research, the authors analyzed data collected from more than three million births in nine countries in North America, South America, Europe, Asia and Australia.

The data was collected from 14 research centers involved in the International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO). The ICAPPO was started in 2007 to study the effects of pollution on pregnancy outcomes.

Most of the data used for this study was collected as part of the ICAPPO during the mid-1990s to the late 2000s. It is the largest study of its kind ever done.

For each birth, the researchers collected information about the baby's weight, dates of conception and birth and air pollution levels for the entire duration of the pregnancy in the city where the pregnancy occurred.

Researchers found that higher levels of air pollution during pregnancy were associated with higher rates of low birth weight babies.

Low birth weight, defined as below 5.5 pounds, is associated with serious health consequences, including increased risk of sickness, earlier death and chronic health problems in later life, said lead author Dr. Dadvand.

“What’s significant is that these are air pollution levels to which practically everyone in the world is commonly exposed,” said co-author Tracey J. Woodruff, PhD, a professor of obstetrics and gynecology and reproductive sciences at the University of California San Francisco.

“These microscopic particles, which are smaller than the width of a human hair, are in the air that we all breathe,” she said.

More research is being conducted on the study participants to see if the mothers' exposure to air pollution would have other health consequences for their children later in life.

The study was published February 6 in the journal Environmental Health Perspectives.

The research was funded by the United States Environmental Protection Agency (EPA), the National Institute for Environmental Health Sciences, the British Columbia (BC) Ministry of Health in Canada, the BC Vital Statistics Agency and the BC Reproductive Care Program.

Additional funding was provided by Wellcome Trust.

The authors reported no potential conflicts of interest.