Health

Global heating linked to early birth and damage to babies’ health, scientists find | Climate crisis

The climate crisis is harming the health of fetuses, babies and infants around the world, according to six new studies.

Scientists have found that increased heat is linked to rapid weight gain in babies, which increases the risk of obesity later in life. Higher temperatures were also linked to premature births, which can have lifelong health effects, and increased hospitalizations of young children.

Other studies have shown that exposure to smoke from wildfires doubles the risk of serious birth defects, while reduced fertility has been linked to 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 very beginning, from preconception, infancy through adolescence, we start to see significant impacts of weather hazards on health,” said Professor Gregory Wellenius, who edited the issue with Amelia Wesselink, both at Boston University School of Public Health, USA.

“It’s a problem that affects everyone, everywhere. These extreme events will become even more likely and severe as climate change continues. [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 has been discovered by scientists in Israel. They analyzed 200,000 births and found that babies exposed to the 20% highest nighttime temperatures had a 5% higher risk of rapid weight gain.

The work has “significant implications for both climate change and the obesity epidemic,” the Hebrew University of Jerusalem researchers said, because early childhood is key in determining adult weight and because obese people may suffer more from extreme heat. “It’s an interesting hypothesis that is definitely worth following,” Wellenius said.

Globally, 18% of children today are overweight or obese. One possible mechanism for 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 wildfires in the month before conception doubled the risk of a birth defect called gastroschisis, where a baby’s intestines and sometimes other organs protrude from the body through a small hole in the skin.

Scientists looked at two million births, including 40% 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 babies. fetus. They found a 28% increased risk of birth defects in mothers living near wildfires during the first trimester of pregnancy.

A woman and her baby escape from the burning village of Platanos
A woman and her baby escape from the burning village of Platanos during the 2007 summer forest fires in Greece. Photograph: Louisa Gouliamaki/AFP/Getty Images

Fetal gastroschisis is rare – there are approximately 2,000 cases per year in the United States. But cases are rising around the world. “Human exposure to wildfires is expected to increase over the next few decades,” said Bo Young Park of California State University. “Therefore, a thorough understanding of the negative health effects associated with wildfires is essential.”

Two new studies have looked at the link between high temperatures and premature births. The first assessed nearly one million pregnant women in New South Wales, Australia, from 2005 to 2014, 3% of whom gave birth before 37 weeks.

Researchers found that those who were in the 5% hottest places in the state during the week before birth had a 16% higher risk of preterm 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] birth is likely to increase with the expected increase in global temperatures and heatwaves – this is a potentially serious concern,” said the researchers, led by Edward Jegasothy of the University of Sydney.

The second study analyzed 200,000 births from 2007 to 2011 in Harris County, Texas — which includes Houston — where people are used to the heat. The period included the hottest summer on record in Texas in 2011.

A quarter of mothers were exposed to at least one very hot day during their pregnancy, days when the temperature reached the top 1% of historical summer temperatures. The risk of premature birth was 15% higher the day after these very hot days, the scientists found. But the risk was even higher for particularly early births, tripling for babies born before 28 weeks, and was also higher for the bottom 20% of mothers.

“Public health warnings during heat waves should include pregnant women, especially given our finding of stronger associations earlier in gestation when the consequences of preterm birth are more severe,” the authors said. researchers, led by Lara Cushing of the University of California, Los Angeles. It’s unclear how heat triggers premature births, but it may be due to the release of labor-inducing hormones.

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

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

Warmer temperatures have also increased the number of admissions of young children to New York’s emergency departments, another new study has found. Scientists looked at 2.5 million admissions over eight years and found that a 7C rise in maximum temperature led to a 2.4% increase in admissions for under-fives. Young children lose proportionally more fluids than adults and their ability to regulate their body temperature is immature, the researchers said.

Burning fossil fuels is driving the climate crisis but also causing air pollution and a new study in Denmark has assessed the impact of dirty air on 10,000 couples trying to conceive naturally. He found that increasing particulate pollution by a few units during a menstrual cycle resulted in a decrease in conception of around 8%.

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

Wellenius said an important aspect of the studies was that they showed vulnerable people often suffered the worst effects, such as people of color and low-income people who didn’t have air conditioning or lived in high-pressure areas. heavy air pollution. “It’s absolutely a matter of health equity and justice,” he said.

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