Climate change may have a bigger impact on pregnancy than we previously thought.


A study recently published in the journal Nature Climate Change sheds some alarming light on the effect temperature has on gestation. Researchers examined 56 million births from 1969 to 1988 and correlated that data to weather data in the areas where the births occurred. They found a spike in deliveries on days where the mercury topped 90 degrees Fahrenheit.

Interestingly, a decline in births in the two weeks following a heatwave or “extreme heat event” was recorded, suggesting that births had occurred earlier than they should have. "That rise, then fall, indicates a forward shift or an acceleration of deliveries and ultimately a loss of up to two weeks gestation for those births," study author Alan Barreca, an associate professor in environmental economics at the University of California, Los Angeles, told NBC News. "If you calculate the average, it's a loss of about six days gestation."

The last few weeks of pregnancy are arguably the worst. Expecting parents have their eyes on the finish line and as the 40-week mark moves closer and the anticipation coupled with the physical demands of late-term pregnancy can make for a brutal experience. Many people believe that things are safe after the 38-week mark—that an early delivery will be no big deal and it just means that they’ll be cuddling their new baby that much sooner.

But those days are important. Babies born around the 38th gestational week, even though they are considered full-term, may have trouble adjusting to breathing instead of being supplied with oxygen through the womb and spend more time in neonatal intensive care.

The study brings to light the very real danger of climate change on a parent’s ability to carry a baby to full gestation.  ACOG, the American College of Gynecology, has described climate change as an “urgent women’s health concern” and Dr. Nathaniel DeNicola, an OB-GYN at George Washington University Hospital, and environmental health expert with ACOG explains, "It's one more study showing a high-level message, which is that extreme temperature is more and more associated with obstetric outcomes, including preterm births and low birth weight.”

Though the exact mechanism behind the relationship between high temperatures and preterm birth is unclear, researchers believe dehydration could play a part. When a person becomes dehydrated, the hormone oxytocin is released. Oxytocin also plays a crucial role during childbirth, but it’s important to note that the study did not find causation only correlation between high temperatures and early birth.

Researchers estimate that around 25,000 heat-related early births occur yearly, resulting in roughly 150,000 lost gestational days and based upon current climate-change projections could end up with the loss of as many as 250,000 gestational days every year.