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Air Pollution Linked to U.S. Birth Defects

WebMD Health News

Dec. 31, 2001 -- One in 33 U.S. babies is born with a serious birth defect. Why so many? Air pollution, says a major new study.

"There seems to be something in the air that can harm developing fetuses," says study leader Beate Ritz, MD, PhD, in a news release. Ritz is an epidemiologist at UCLA.

The huge study analyzed data of more than 9,000 babies born from 1987 to 1993 in southern California. The researchers measured air quality near the homes of babies born with and without birth defects.

The results: women in areas with the worst air pollution were three times more likely to have a baby with a serious heart defect than women in areas with clean air. Women in areas with more moderate air pollution were twice as likely to have a baby with a serious heart defect. This type of birth defect almost always means surgery before the child is 1 year old.

The increased risk of birth defects was seen only in women who breathed bad air during the second trimester of pregnancy. This is the crucial time when the complex structure and function of the heart and other organs develop.

"The fact that certain heart defects are turning up in the second month of pregnancy when hearts are being formed suggests something serious may be happening," says study co-author Gary Shaw, DrPH.

Shaw, a researcher in the current study, notes that increasing levels of air pollution are linked to increasing levels of birth defects. This, he says, strengthens the study findings and means that urgent research is needed.

"We need answers," he says.

The study found that high levels of carbon monoxide and ozone were linked to birth defects. Whether it is these contaminants -- or something else in the air -- remains unknown.

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