Pregnancy and Excessive Heat: Avoiding Risks of Serious Complications

Exposure to excessive heat can be harmful, if not dangerous, for pregnant women, including causing hypertensive disorders of pregnancy and other serious complications. “As little as one day of high heat may increase risks,” states the U.S. Centers for Disease Control and Prevention (CDC).

As record high temperatures or heat indices are being felt this summer across the nation, more attention needs to focus on staying cool and hydrated during pregnancy, public health officials say. While physical activity and exercise in pregnancy are associated with minimal risks and have been shown to benefit most women, doing so in extreme heat can have the opposite effect.

“In pregnancy, you are more susceptible to overheating,” explains Natalia Echeverri Botero, M.D., obstetrician gynecologist at Baptist Health South Miami Hospital. “And it can cause complications during your pregnancy.”

Natalia Echeverri Botero, M.D., obstetrician gynecologist at Baptist Health South Miami Hospital.

 

When the heat and humidity is overwhelming, it’s best to avoid outdoor activities during pregnancy. But with proper hydration, some activity is beneficial if you avoid the heat’s peak time-frame. Early mornings or evenings usually offer the best time-frames for exercising outdoors. The key is to avoid the sun’s harmful UV (ultraviolet) radiation at the peak of the day, roughly 10 a.m. to 4 p.m.

“What do I usually tell my patients? I tell them that I want them moving always, but I want them also to avoid the heat,” said Dr. Echeverri. “So, when they're going for walks or going outside, I want them going early in the morning or late in the afternoon. Heat can place added stress on the heart and cardiovascular system, which is already undergoing normal physiologic changes during pregnancy, including increased blood volume, cardiovascular output, and heart rate.”

Most people, even those in top physical condition, can suffer heat-related illness in peak times of the day during heat waves. Pregnancy can make a person even more likely to get heat exhaustion, heat stroke, or other heat-related illness sooner than those who are not pregnant, states the CDC. This is because the body must work harder to cool down – and that applies to the mother and the developing baby. Pregnancy can also make you more likely to become dehydrated.

“They're going to overheat easily which can cause low blood pressure, to start off with, or fainting spells,” adds Dr. Echeverri. “What's the most common complaints I get? After a baby shower, or after your maternity shoot (photo session), is: ‘I got dizzy. I had to sit down. Do I need to come in?’ And it's usually because it was done outside in our beautiful areas of Miami -- and patients got overheated.”

Heat exposure in any trimester has been associated with adverse pregnancy outcomes including preterm births, stillbirths, and low birthweight infants, states the CDC.

“Once you hit your third trimester, overheating can cause pre-term contractions which can actually be very serious,” adds Dr. Echeverri. “What I tell my patients is that they have to be mindful when they're pregnant. I want them to take walks, but I want them to do it early or late in the day -- and then they really need to stay hydrated.”