Climate change could push CHD rates 62% higher by 2035

A projected increase in extreme weather driven by climate change could have a lasting effect on expectant mothers and their children, according to a study that recently linked maternal heat exposure to an elevated risk of congenital heart defects (CHDs) in the U.S.

Corresponding author Shao Lin, MD, PhD, and colleagues said existing health-related climate projection studies tend to focus on big-picture issues like cardiovascular and respiratory diseases rather than pregnancy outcomes, but women’s exposure to extreme heat could have important implications for the health of future generations.

“Maternal heat exposure during early pregnancy may directly cause fetal cell death or interfere with protein synthesis via heat-shock proteins and induce severe fetal malformations, as observed in animal studies,” Lin, a professor at the University of Albany, and co-authors wrote in the Journal of the American Heart Association Jan. 30. “As global temperatures continue to rise, more intense, frequent and longer-lasting heat events are expected.”

Last year, Lin and a team of researchers reported a positive relationship between CHDs and maternal heat exposure during a woman’s critical gestational period (three to eight weeks post-conception) in spring and summer in the U.S. The study, published in Environment International, gauged the risk of CHDs based on maternal heat exposure for births that took place between 1997 and 2007.

The present analysis expanded on that study, projecting nationwide changes in maternal heat exposure during early pregnancy and changes in CHD burden between 2025 and 2035. Using climate change forecast data from NASA and the Goddard Institute for Space Studies, Lin et al. simulated changes in daily maximum temperatures by geographic region and calculated the anticipated maternal heat exposure per region for spring and summer.

The authors found the greatest percentage increases in the number of newborns with CHDs would take place in the Midwest, which they estimated would see a 62.4 percent increase in CHD prevalence as a result of global climate change. The Northeast was next, with a projected 19.3 percent increase, followed by the South (16.6 percent increase), Southwest (12.7 percent increase), Southeast (5.6 percent increase) and West (3.2 percent increase).

“Regardless of the definition used for heat exposure, increases were projected for all pregnant women in all regions and in both spring and summer, as well as for all exposure metrics,” Lin and co-authors wrote. “These increases were projected to be stronger in the Midwest and Northeast regions in summer. We also found that populations in the South and Southwest may experience similar increases in heat exposure in spring.”

They said the potential increases in both the number of pregnant women in the U.S.—the national rate is expected to jump 5 percent by 2030—and the number of excessively hot days underlines the “alarming effect” that climate change could have on reproductive health.

“Generally, all weather-related diseases are preventable,” the authors wrote. “Understanding maternal heat exposure and the associated CHD burden under future climate scenarios will assist in guiding public health practitioners to develop early warning and preparedness programs to modify behaviors with the aim of reducing CHD burden.”