May 29, 2024 - Health

Heat waves increase risk of early births, study finds

Illustration of a 3D health cross shape dripping and melting from heat.

Illustration: Aïda Amer/Axios

The rates of premature and early-term births slightly increase after heat waves, and the risk grows as extreme temperatures last longer, according to a new study of 25 years of birth data.

Why it matters: It's one way that extended heat waves, which have grown more common with climate change, may be harmful to infant health, the study in JAMA Network Open suggests.

  • Premature birth is the most common cause of death for infants and can lead to many long-lasting health challenges.

What they found: After four straight days of abnormally high temperatures, there's a 2% higher chance of babies being born prematurely (before 37 weeks). The chance is 1% higher for early-term births (37-38 weeks).

  • The risk was slightly higher among Black and Hispanic mothers and those with less education.
  • Researchers analyzed 53 million births during the spring and summer between 1993 and 2017 in the 50 most populous U.S. metropolitan areas.
  • Researchers said their study is the largest yet of the association between extreme heat and perinatal health.

Go deeper: Extreme heat's health consequences

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