New Studies on the Effect of Extreme Heat on Pregnancies. Science: EXPECTING EXTREMES

[NNadir]

This is a news item from the journal Science: EXPECTING EXTREMES

Subtitle:

Intense heat is a particular hazard in pregnancy. New studies are probing why

Science 28 SEP 2023 BY MEREDITH WADMAN

I'm not logged in to my account, and can read the article, thus it's probably open sourced, but a few excerpts are in order:

SYDNEY—Jem Cheng was soaked with sweat by the time she climbed off the stationary bike at the University of Sydney last month. The work of pedaling wasn’t the problem; the 30-year-old pushes herself much harder during her own regular workouts. But this ride took place in a “climate chamber,” a large, high-ceilinged room that on this day was heated to 36°C. During Cheng’s 86 minutes of pedaling, the humidity in the chamber gradually ramped up from 38% to a deeply uncomfortable 56%, making the air feel more like 46°C.

“I feel like I could have stayed in there for a little bit longer,” she said later, after weighing in to discover she had sweated off nearly 1 kilogram. “But I probably wouldn’t have wanted to...”

...But starting soon, dozens of pregnant women will be pedaling in the same climate chamber. The groundbreaking study seeks to replicate what tens of millions of pregnant people experience every day in a warming world: physical exertion in intense heat. The trial is funded by £2 million from the Wellcome Trust, which awarded £16.5 million this year to projects probing why heat is a risk during pregnancy.

That risk is already undeniable. Dozens of epidemiological studies have linked heat exposure to poor outcomes including preterm birth, low birth weight, stillbirth, and congenital anomalies in the fetus. Premature birth is the most commonly documented: A 2020 literature review found that each 1°C increase brought a 5% increase in the risk of prematurity in hot areas or seasons—and a 16% increase during heat waves. That means climate change could exacerbate a major risk: Globally, prematurity is already the leading cause of death for children younger than 5.

A smaller number of studies, almost all from high-income countries, has suggested heat exposure also imperils the pregnant person: It has been associated with gestational diabetes and preeclampsia, a dangerous condition marked by high blood pressure...

...UNCOMFORTABLE INDOOR cycling hardly captures the kinds of heat exposure facing women in rural Kilifi County in Kenya, one site in a multicountry study called Climate, Heat and Maternal and Neonatal Health in Africa, better known as CHAMNHA...

... In this drought-ridden region where high temperatures average 31°C for months at a time, most women have no choice but to work in direct sun, collecting firewood, farming, and walking daily to ever-scarcer water holes, while trying to avoid those shared with animals for fear contaminants will harm their fetuses. (That reluctance puts both mother and fetus at risk of dehydration.) Pregnant women experienced sleeplessness, racing hearts, and faintness, and described their bodies as “boiling” or “on fire.” Some men said they had seen their wives having difficulty breathing because of the heat. Anecdotally, community health workers reported, pregnancies in the hottest months were more likely to be complicated by high blood pressure, or to end in miscarriages or premature birth...

Animal studies in sheep and cows reported in the article indicate that high temperatures lead to reduced placental size, poorer blood flow, lower oxygenation, and increased still birth, low birth weight and other complications.

Have a nice weekend.

[slightlv]

1. Wow... this is really interesting... and especially interesting given my own personal experience in

South Texas while pregnant and problems with pregnancy that I never understood. Thank you for the article. It may not have been the exact cause... but it sure gives me pause for thought.