Study suggests that high temperatures can cause women to give birth prematurely. A phenomenon that could worsen with global warming.
When the heat exceeds 30°C, childbirth is accelerated, claimed Spanish researchers in 2013. This study, carried out by a team from the Barcelona University Hospital, had to l period involved approximately 8,000 births . A recent study, published in the journal Nature climate change now confirms these conclusions. This new work suggests that temperatures above 32°C can lead to thousands of premature births each year in the United States.
For this study, researchers from the University of California focused on the evolution of the birth rate in the various American counties. The data covered a 20-year period from 1969 to 1988, encompassing approximately 56 million births . After analysis, it emerged that the birth rate increased on average by 5% days when the maximum temperature was above 32.2°C. Delivery also occurred on average six days earlier , with some occurring up to two weeks before the originally scheduled date.
“We find that high heat leads to an increase in deliveries on the day of exposure and the following day, and that additional births have been accelerated by up to two weeks , explain the researchers. We estimate that an average of 25,000 infants per year are born earlier due to heat exposure, with a total loss of over 150,000 gestational days per year” .
To explain these results, the researchers suggest that high temperatures affect oxytocin. This hormone is indeed involved in regulating the onset of childbirth. Extreme heat can also harm the cardiovascular system of the women concerned, which can also induce premature labor.
The consequences of these preterm births are still largely misunderstood. However, some studies have suggested that infants have more medical problems and higher hospital costs than term infants. In view of these results, and taking into account recently established climate projections, the researchers emphasize the need to predict the potential impact of global warming on the health of infants.
Alan Barreca, lead author of the study, found these potential impacts of climate on early birth rates particularly concerning. “We predict that more than one in 100 births will occur earlier than expected in the United States by the end of the century , he explains. This number may seem small, but it is much higher than the chances of having a car accident “.
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