As global temperatures rise so may the number of premature births - study

Pregnant woman having sonogram
Photo credit: Getty.

As temperatures around the globe rise, scientists continue to warn of the vast challenges hotter weather will bring.

Melting glaciers, rising sea levels and species extinction are just some of the problems expected to worsen as the world moves closer to what scientists call a "tipping point".

But now, there is another thing to add to the list of climate-change related problems: premature births.

According to a new study published in Nature Climate Change, hot temperatures may lead to babies being born earlier, meaning the number of babies born prematurely could rise in coming years.

Researchers looked at a sample of 56 million live births in the United States to see what impact hotter weather had on when babies are born.

They found that between 1969 and 1988 extreme heat caused an estimated 25,000 babies to be born earlier than they otherwise would have been.

On average the babies were born 6.1 days earlier, though in some cases babies came out of the womb two weeks earlier, researchers Alan ­­Barreca and Jessamyn Schalle said.

Barreca and Schalle used estimated shifts in daily birth rates from counties across the United States to calculate the total number of lost days of gestation.

On days with a maximum temperature above 32.2C, the birth rates increase by 5 percent, the authors found. 

They also referred to existing studies that show extreme heat in the second and third trimester led to lower birth rates.

The authors concluded that based on projections of climate change, an additional 250,000 gestational days could be lost annually by the end of the century.

"While we posit climate change will cause gestational losses, the exact magnitude of the future costs is highly uncertain - households may adapt as expectations about the frequency of hot weather events increase, which could mitigate impacts on infant health," the authors wrote.

The study comes after scientists last week warned the planet was edging dangerously close to a "tipping point", which once crossed would lead Earth past the point of no return.

"The stability and resilience of our planet is in peril," the authors of that report concluded.