Pregnant women exposed to high heat face serious labor and delivery risks, new study says

Women are at increased risk of serious problems during labor and delivery while exposed to hot weather, a study released Thursday found.

The study of more than 400,000 medical records, published in JAMA Network Open, found that women exposed to high heat were significantly more likely to experience “severe maternal morbidity,” which the Centers for Disease Control and Prevention defines as unexpected outcomes of labor and delivery that lead to significant short- or long-term health consequences for the mother. Health problems increased with the extremity of the heat, the study found.

Previous studies have linked extreme heat to preterm birth, premature rupture of membranes, low birthrate and still birth.

Dr. Victor Klein, a Northwell Health specialist on high-risk pregnancies, said more women come to his office or are admitted to the hospital during hot weather.

“Heat will stress your system,” he said in an interview.

And risk is higher in the heat among pregnant women who have health problems, he said.

“Those people who are overweight, they’re older, they have heart disease, they have hypertension — they’re at increased risk of bad things happening due to weather, forget about being pregnant,” said Klein, who was not involved with the study.

Klein sees more patients than in the past who have children later in life, such as in their 40s, and who have high blood pressure, cardiovascular disease, diabetes and other health conditions that increase the possibility of problem pregnancies.

Heat-related illnesses during pregnancy can lead to complications for the baby if they lead to a premature birth, Klein said. He recommends that pregnant women drink lots of fluids, don’t exert themselves outdoors during high temperatures and stay inside with air conditioning.

Another study, published last year on medRxiv, found that women exposed to very hot temperatures both before and during pregnancy were more likely to experience severe maternal morbidity.

Severe maternal morbidity has been increasing in recent years, the CDC says, with rates twice as high among Black than white women, studies have found.

The heat can also harm young children, said Dr. Marc Lashley, a pediatrician in Valley Stream with Allied Physicians Group.

Kids who are physically active outdoors are at higher risk for heat-related illness, and “in extreme heat, the younger the child, the more vulnerable they are," he said.

“Infants are very vulnerable,” Lashley said. “They don’t have a lot of backup systems to help them. They can’t sweat profusely like we can."

By David Olson

david.olson@newsday.com@DavidOlson11

David Olson covers health care. He has worked at Newsday since 2015 and previously covered immigration, multicultural issues and religion at The Press-Enterprise in Southern California.