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More babies born with congenital heart defects predicted

US researchers predict that a larger number of babies will be born with congenital heart defects between 2025 and 2035 due to their mothers' exposure to higher temperatures, triggered by climate change, while pregnant.

Heat and pregnancy do not mix. High temps don't just make a pregnant woman uncomfortable, the heat can actually hurt the health of her baby – and with climate change, this will probably become a bigger problem.

Researchers found that a larger number of babies will probably be born with congenital heart defects between 2025 and 2035 due to their mothers' exposure to higher temperatures, triggered by climate change, while pregnant. This especially holds true for moms who were pregnant through spring or summer. Climate change could result in as many as 7,000 additional cases of congenital heart defects in the US over an 11-year period, according to the study. The Midwest will probably see the biggest percent increase, followed by the South and Northeast regions of the US.

Earlier research found that climate change could "halt and reverse" progress made in human health over the past century, but there's more limited research on the impact that has on pregnancy, the authors said. Congenital heart defects are the most common type of birth defects and can hurt a baby's overall health and potentially impact how their body works or develops.

"The potential increases in both the number of pregnant women and maternal heat exposure suggest an alarming effect that climate change may have on reproductive health," the study said.

Researchers figured this out by looking at data collected in the National Birth Defects Prevention Study, a large multi-state, population-based study that investigated risk factors for major structural birth defects. They also looked at climate data from the US government.

Based on climate data projections, the entire US will face higher temperatures. New York, Midwest states such as Iowa and south-eastern states such as Georgia and North Carolina will probably see greater temperature increases. There will be greater variation in temperature for southern states such as Texas and Arkansas and out west in states such as California in the summer months.

It's unclear what the link is between high temperatures and congenital heart problems. Animal studies found that heat can cause foetal cell death and can negatively impact the proteins that play a crucial role in foetal development.

This current research builds on earlier work that found when the temperature stays high, it can hurt a mother's chances of carrying a baby to term. Extreme heat also puts moms at risk to give birth early. Moms exposed to high heat have a bigger chance of having a baby that's small or underweight. Mothers who endure high temperatures early in their pregnancy have a much greater risk that their baby will have congenital heart problems, earlier research has found.

"Our findings underscore the alarming impact of climate change on human health and highlight the need for improved preparedness to deal the anticipated rise in a complex condition that often requires lifelong care and follow-up," said study author Dr Shao Lin, a professor in the School of Public Health at the University of Albany. "Although this study is preliminary, it would be prudent for women in the early weeks of pregnancy to avoid heat extremes similar to the advice given to persons with cardiovascular and pulmonary disease during heat spells."


Background: More intense and longer‐lasting heat events are expected in the United States as a consequence of climate change. This study aimed to project the potential changes in maternal heat exposure during early pregnancy (3–8 weeks post conception) and the associated burden of congenital heart defects (CHDs) in the future.
Methods and Results: This study expanded on a prior nationwide case‐control study that evaluated the association between CHDs and maternal heat exposure during early pregnancy in summer and spring. We defined multiple indicators of heat exposure, and applied published odds ratios obtained for the matching season of the baseline (1995–2005) into the projection period (2025–2035) to estimate potential changes in CHD burden throughout the United States. Increases in maternal heat exposure were projected across the United States and to be larger in the summer. The Midwest will potentially have the highest increase in summer maternal exposure to excessively hot days (3.42; 95% CI, 2.99–3.88 per pregnancy), heat event frequency (0.52; 95% CI, 0.44–0.60) and heat event duration (1.73; 95% CI, 1.49–1.97). We also found large increases in specific CHD subtypes during spring, including a 34.0% (95% CI, 4.9%–70.8%) increase in conotruncal CHD in the South and a 38.6% (95% CI, 9.9%–75.1%) increase in atrial septal defect in the Northeast.
Conclusions: Projected increases in maternal heat exposure could result in an increased CHD burden in certain seasons and regions of the United States.

Wangjian Zhang, Tanya L Spero, Christopher G Nolte, Valerie C Garcia, Ziqiang Lin, Paul A Romitti, Gary M Shaw, Scott C Sheridan, Marcia L Feldkamp, Alison Woomert, Syni‐An Hwang, Sarah C Fisher, Marilyn L Browne, Yuantao Hao, Shao Lin, Charlotte Hobbs, Suzan Carmichael, Jennita Reefhuis, Sarah Tinker, Marlene Anderka, Charlotte Druschel, Erin Bell, Andy Olshan, Robert Meyer, Mark Canfield, Peter Langlois, Lorenzo Botto

[link url=""] report[/link]
[link url=""]Journal of the American Heart Association abstract[/link]

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