A study published Tuesday in the British journal Nature Climate Change provides important evidence that climate change affects the health of infants. U.S. scientists have found that hot weather can lead to an increase in the number of births on the day, and some delivered even two weeks earlier. The researchers caution that this is expected to continue by the end of the century.
Increased exposure to hot weather for pregnant women due to climate change may harm the health of infants, but the extent of this threat has not been documented. The researchers believe that shorter pregnancies are associated with poor health and cognitive well-being later in life. Previous studies have shown that hot weather can lead to faster childbirth and shorter pregnancies. This is because high temperature can cause pregnant women in a state of thermal regulation failure, contraction, in addition to dehydration can also cause uterine blood supply to reduce, so that the secretion of pituitary hormone increases, thus inducing early delivery. But it has long been unclear how much the heat would lead to a reduction in the number of pregnancies.
This time, Alan Barika and Jesmyn Schuler, scientists at the Ucla U.S. Institute for Environment and Sustainability, used estimates of changes in daily birth rates in U.S. counties to quantify the number of high-temperature-related pregnancy days over 20 years. The survey found that from 1969 to 1988, an average of 25,000 babies were born early in the United States each year due to hot weather, resulting in an annual reduction of more than 150,000 pregnancy days.
The team’s sample covered 56 million births in more than 3 million prefecturedays. They estimate that on days when the maximum temperature exceeds 90 degrees F (32.2 degrees C), the birth rate will increase by 5% and the number of days of pregnancy will decrease by an average of 6.1 days. Some deliveries occur two weeks early.
The team concluded that by the end of the century, another 250,000 days of pregnancy were expected to be reduced each year.
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We already know that global warming will cause temperatures to rise at the poles, melt glaciers, deprive polar bears of their homes, flood some distant islands, and migrate plants and animals to higher latitudes… But what we didn’t expect was that it had quietly affected human childbirth. High temperatures can bring babies into the world a few days early, which can affect the health and cognitive abilities of the fetus. It sounds surprising that few people associate temperature with birth. The consequences of climate change are so complex that we may have missed too many signals. Similar hidden correlations do require more research to analyze and verify.