Atlantic, Atlantic Media Company
By Ellie Kincaid
A handful of researchers in the United States, Canada, and elsewhere are methodically accumulating evidence suggesting that higher temperatures could be linked to a higher risk of premature births, stillbirths, or other negative pregnancy outcomes. The findings in each case, while compelling, still raise as many questions as they seem to answer, and all the researchers say that much more work needs to be done. But they also suggest that enough evidence has already surfaced to warrant increased scrutiny—particularly as global warming is expected to drive average temperatures ever upward over coming decades.
“In the future,” said Rupa Basu, chief of air and climate epidemiology at the California Environmental Protection Agency, “this is going to be a growing public-health concern.”
A decade ago, Basu noticed something odd in the scientific literature documenting the health risks of air pollution—a much clearer and well-established relationship. She knew that past research, including some of her own, had shown a link between air pollution and negative pregnancy outcomes, but while the literature alluded to a seasonal pattern, none of the studies controlled for temperature. “I said that some of this must be due to temperature,” Basu recalled, “but we don’t have any data to support that.”
Basu first started to explore the effects of temperature on premature births. Using birth-certificate data from California’s Office of Vital Records, she matched more than 58,000 preterm births occurring during the warm months from 1999 through 2006 with climate data from the state Irrigation-Management Information System and U.S. EPA Air-Quality System. She also pulled air-pollution data from the California Air-Resources Board to assess whether levels of ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, or smokelike particles were confounding or changing the relationship between temperature and premature births.