Climate Change May Increase Risk of Heart Defects in Babies

BY ON February 5, 2019

pregnant woman holding red heart

Any mom who has experienced heat exposure while pregnant knows just how harrowing it can be. Having entered the last trimester of my pregnancy during a summer in San Diego with unreliable air conditioning, I still remember how uncomfortable and vulnerable I felt.

That feeling wasn’t entirely misplaced: Extreme heat exposure can trigger premature birth and other health issues in both pregnant women and babies. According to a 2018 study, exposure to heat in pregnancy can even increase the risk of congenital heart defects (CHDs) in newborns.

The risk of CHDs is especially heightened if a pregnant mother is exposed to extreme heat during postconceptional weeks 3-8, according to research. And as temperatures steadily climb due to climate change in the coming decades, the effects could show up even in our babies’ hearts.

According to a recent study in the Journal of the American Heart Association, there is a strong possibility that a larger number of infants will be born with congenital heart defects between 2025 and 2035.  Study authors write,

“The potential increases in both the number of pregnant women and maternal heat exposure suggest an alarming effect that climate change may have on reproductive health.”

Researchers arrived at this conclusion through analysis of data from the National Birth Defects Prevention Study. Study authors estimate that, over the 11-year period, up to 7,000 additional babies in certain regions of the U.S. could develop congenital heart defects due to their pregnant mothers’ exposure to climate change-related high temperatures.

Researchers believe that the states with the highest risk of larger numbers of infants with congenital heart defects due to climate change will be concentrated in the Midwest (especially Iowa), with New York, Arkansas, Texas, California, Georgia, Utah, and North Carolina following closely behind.

The effects will be strongest in regions with high variations in temperature. They will also be exacerbated if mothers experience those crucial first months of pregnancy during spring and summer, when they are likelier to be exposed to the most extreme effects of climate change—including higher, “more intense, frequent, and longer-lasting heat events,” write the study’s authors.

It’s not yet clear exactly why exposure to extreme heat in early pregnancy is associated with higher rates of congenital heart defects. Results from animal studies suggest that heat leads to fetal cell death and interferes with the health of essential proteins associated with early development.

The new study highlights the potential significance of climate change on public health. Indeed, study author Dr. Shao Lin told CNN:

“Our findings underscore the alarming impact of climate change on human health and highlight the need for improved preparedness to deal the anticipated rise in a complex condition that often requires lifelong care and follow-up.”

Heart disease and defects are common health problems that should concern all of us. Heart disease is the number one killer of women, and congenital heart defects are the most common of all birth defects. CHDs can affect infant morbidity and mortality, as well as development and projected quality of life. An increasing number of Americans are dying from cardiovascular disease, whether congenital or acquired. And as the effects of climate change spread, these effects could take a toll on the most vulnerable among us.

Laura Dorwart



Laura Dorwart is a writer and editor with bylines at The New York Times, The Guardian, VICE, SELF, HuffPost, McSweeney’s, and many others. Learn more:


TOPICS: California, Children's Health, Climate Change, Georgia, Heat and Extreme Weather, New York, North Carolina, Texas, Utah