More Bad News: Study Suggests Hotter Temperatures Lead to Pre-Term Labor

Researchers found that unusually high temperatures reduced gestation time by about 6.1 days.
Hannah Smothers
Brooklyn, US
A pregnant person lays awake in bed

Climate change is going to kill most things: you, me, the internet, the economy, society, the planet… Humans messed with the planet and the planet is now messing with us back, in the form of a slow and probably very painful death. And a new study published Monday in Nature identifies another potential hazard of climate change: an increase in preterm births. On average, the researchers found that unusually high temperatures cost babies about 6.1 days' gestation time.


The study showed that more babies are born before the 40-week mark when outside temperatures rise above 80 degrees, and there is an even more dramatic increase (of about 0.97 births per 100,000 women) when temps exceed 90 degrees. The effects of hot weather on labor were diminished in places that are hot most of the time, leading researchers to believe that people who are acclimated to high temps aren’t affected as severely. While researchers note that it’s not totally clear how hotter weather might jumpstart preterm labor, a few theories are that heat leads to greater cardiovascular stress, which can induce labor; can stimulate production of oxytocin, a hormone that surges during labor; and can disrupt sleep, increasing the risk for early birth. There’s also an unsurprising class divide: Wealthier people, with better in-home air conditioning, were less likely to go into preterm labor on a particularly hot day.

Researchers arrived at their findings by looking at county-by-county birth records across the United States between 1969–1988. The dataset is a bit limited because, in 1989, birth data became a little bit more private and is harder to analyze, according to Time . But the slightly old dataset is interesting, because things have only gotten hotter in the past 30 years. Average temperatures have increased by at least 1.5 degrees since 1980, according to NASA. The oceans hit their warmest-ever temperatures just last year, and the latest report from the United Nations’ International Panel on Climate Change predicts more temperature increases over the next 100 years. It’s hot now, and only going to get hotter, and that has very real repercussions for just about every aspect of our lives.

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