Sat. Jan 22nd, 2022

The climate crisis is damaging the health of fetuses, babies and infants worldwide, six new studies have found.

Researchers discovered that increased heat was associated with rapid weight gain in babies, increasing the risk of obesity later in life. Higher temperatures were also associated with premature birth, which can have lifelong health effects, and with increased hospitalizations of young children.

Other studies showed that exposure to smoke from forest fires doubled the risk of serious birth defects, while decreased fertility was associated with air pollution from burning fossil fuels, even at low levels. The studies, published in a special issue of the journal Pediatric and Perinatal Epidemiology, spanned the globe from the United States to Denmark, Israel and Australia.

“From the beginning, from preconception, through early childhood to adolescence, we have begun to see important effects of climate change on health,” said Professor Gregory Wellenius, who co-edited the issue with Amelia Wesselink, both of the Boston University School of Public Health in the United States. .

“This is a problem that affects everyone, everywhere. These extreme events will become even more likely and more serious with continued climate change. [and this research shows] why they are important to us, not in the future, but today. “

The link between heat and rapid weight gain in the first year of life was found by scientists in Israel. They analyzed 200,000 births and found that babies exposed to the highest 20% of night temperatures had a 5% higher risk of rapid weight gain.

The work has “important implications for both climate change and the obesity epidemic,” said researchers at the Hebrew University of Jerusalem, because infancy is crucial in determining adult weight and because obese people suffer more in extreme heat. “It’s an interesting hypothesis that is very much worth following up on,” Wellenius said.

Globally, 18% of children are now overweight or obese. One possible mechanism for the rapid infant weight gain is that less fat is burned to maintain body temperature when the ambient temperature is higher.

A California study found that a mother’s exposure to forest fires in the month before conception doubled the risk of a birth defect called gastroschisis, in which a baby’s intestines and sometimes other organs protrude from the body through a small hole in the skin.

The researchers examined two million births, 40% of them to mothers living within 15 miles of a wildfire, and the resulting air pollution, which was already known to be harmful to pregnant women and their fetuses. They found a 28% increase in the risk of birth defects in mothers who lived close to forest fires during the first trimester of pregnancy.

A woman and baby escape the burning village of Platanos
A woman and baby escape the burning village of Platanos during Greece’s summer fires in 2007. Photo: Louisa Gouliamaki / AFP / Getty Images

Fetal gastroschisis is rare – there are about 2,000 cases a year in the United States. But cases are rising all over the world. “Human exposure to wildfires is expected to increase in the coming decades,” said Bo Young Park, of California State University. “Therefore, a thorough understanding of the negative health outcomes associated with forest fires is crucial.”

Two new studies examined the association between high temperatures and preterm birth. The first estimated nearly one million pregnant women in New South Wales, Australia, from 2005 to 2014, 3% of whom gave birth to their babies before 37 weeks.

The researchers found that those in the warmest 5% of places in the state in the week before birth had a 16% higher risk of premature birth. Previous research had found a similar effect in the warmer subtropical city of Brisbane, but this was the first in a more temperate region of Australia.

“The risk of [premature] births are likely to increase with the expected rise in global temperatures and heat waves – this is a potentially serious concern, “said the researchers, led by Edward Jegasothy at the University of Sydney.

The second study analyzed 200,000 births from 2007-2011 in Harris County, Texas – which includes Houston – where people are used to heat. The period included Texas’ hottest summer ever in 2011.

A quarter of mothers were exposed to at least one very hot day while pregnant, days when the temperature reached the top 1% of historic summer temperatures. The risk of any premature birth was 15% higher the day after those very hot days, the researchers found. But the risk was even higher for especially premature births, tripling for babies born before 28 weeks, and was also higher for the most disadvantaged 20% of mothers.

“Public health warnings during heat waves should include pregnant people, especially given our discovery of stronger contexts earlier in pregnancy when the consequences of premature birth are more severe,” said the researchers, led by Lara Cushing, of the University of California, Los Angeles. How heat triggers premature births is not known, but it may be due to the release of birth-causing hormones.

This new research adds weight to a 2020 review of 68 studies, comprising 34 million. births that linked heat and air pollution to higher risk of preterm birth, low birth weight and stillbirth. Bruce Bekkar, an author of the review and retired obstetrician, said: “We have already weakened generations from birth.”

Wellenius said: “Even moderate levels of heat can affect the developing fetus, pregnancy complications and children and adolescents. Although the risk to an individual is modest because so many people are exposed, the total number of excess events, whether they are premature births or death, significantly. “

Warmer temperatures also increased the number of admissions of young children to emergency rooms in New York City, another new study found. The researchers looked at 2.5 million admissions over eight years and found that a 7 degree increase in maximum temperature led to a 2.4% increase in admissions in under fives. Young children lose proportionately more fluid than adults, and their ability to regulate their body temperature is immature, the researchers said.

The burning of fossil fuels drives the climate crisis, but also causes air pollution, and a new study in Denmark assessed the effect of dirty air on 10,000 couples trying to conceive naturally. It found that increases in particle pollution of a few units during a menstrual cycle led to a decrease in conception of about 8%.

A recent study in China also showed that air pollution significantly increased the risk of infertility, but the average pollution level was more than five times higher than in the Danish study. “Air pollution [in Denmark] was low and almost exclusively at levels considered safe by the EU, ”said Wesselink. “Current standards may be insufficient to protect against adverse reproductive health effects.”

Wellenius said an important aspect of the studies was that they showed that vulnerable people often suffered the worst consequences, for example colored people and low-income people who did not have air conditioning or lived in areas with higher air pollution. “This is definitely a matter of health and justice,” he said.

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