Disclosures: The authors report no relevant financial disclosures.
July 02, 2020
2 min read

Air pollution, heat exposure linked to pregnancy-related risks

Disclosures: The authors report no relevant financial disclosures.
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A systematic review showed that “common environmental exposures exacerbated by climate change” — namely, air pollution and heat exposure — are significantly associated with adverse pregnancy outcomes, researchers reported.

Rupa Basu

Rupa Basu, PhD, chief of air and climate epidemiology at the California Office of Environmental Health Hazard Assessment, and colleagues found 1,851 articles that matched search terms related to fine particulate matter (PM2.5), ozone and heat in relation to preterm birth, low birth weight and stillbirth, including 68 that met the study criteria — 58 dealing with air pollutants and 10 dealing with heat. They analyzed 32,798,152 births, with a mean of 565,485 births per study.

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“By compiling the evidence, by having several studies showing basically the same thing in different populations, we're showing that the association is real,” Basu told Healio. “It is a public health challenge and really needs to be addressed.”

Of the 58 studies on air pollutants, 84% found a significant association air pollution exposure and adverse birth outcomes, according to the review.

“As far as environmental exposures go, we don't usually see estimates so high,” Basu said. “It was a very clear association. That was pretty surprising to me.”

Of the 10 studies that examined the association between heat exposure and birth outcomes, nine found a significant association between heat exposure during pregnancy and adverse birth outcomes, the researchers reported.

“I was expecting to see maybe some associations, but I wasn't expecting to see such a high association,” Basu said. “Before this, heat was really [a greater risk for the elderly], and that was really the only population that we thought could be an increased risk. There was some evidence for infants, young children, but really it was so much focused on the elderly.”

According to Basu and colleagues, 10 studies reported an increased risk for preterm birth in minority groups. Eight of the 10 noted higher risk for Black mothers, the most consistent subgroup finding.

“We're trying to show all pregnant women who are at increased risk for these pregnancy outcomes that there's a disparity by race or ethnic group,” Basu said. “The main goal is to really highlight pregnant women in a high-risk group to heat and also air pollution. Even though we have been doing this research for [more than] 10 years, it just doesn't seem to be reaching the general public.”