Researchers are predicting that the protracted heatwaves associated with climate change – and which are breaking records in the Australian summer in progress – will lead to a rise in congenital heart defects (CHD) in unborn babies.
The research, published in the Journal of the American Heart Association, and which constrained its predictions to the US, built on previous studies that found exposure to extreme heat events was associated with atrial septal defects and ventricular septal defects – holes in the wall separating the upper and lower chambers of the heart respectively.
The greatest risk occurs in the three to eight weeks following conception.
“Our results highlight the dramatic ways in which climate change can affect human health and suggest that paediatric heart disease stemming from structural heart malformations may become an important consequence of rising temperatures,” said the leading author Dr Wangjian Zhang, a post-doctoral research fellow at the University of Albany.
The projected increase in children with congenital heart disease will pose greater demand on the medical community caring for newborns and well into their lives.
Other complications abound
Exposure to extreme heat events has also been linked to pre-term and low-weight births.
Separate studies have found mothers exposed to heat during early pregnancy can develop hyperthermia, or extremely high body temperature, which increases the risk of having babies with defects of the brain or spinal cord.
In other words, global warming is likely to have an increasingly negative impact on future generations in-utero – affecting many thousands of babies around the world.
The precise mechanisms that cause the heat-induced heart defects remain unclear. Studies in animals suggest heat may cause foetal cell death or interfere with several heat-sensitive proteins that play a critical role in foetal development.
The latest study used climate change forecasts obtained from NASA and the Goddard Institute for Space Studies. Researchers improved the spatial and temporal resolutions of the forecasts, simulated changes in daily maximum temperatures by geographic region and then calculated the anticipated maternal heat exposure per region for spring and summer.
As many as 7000 new cases in the US alone
Based on projections of the number of births between 2025 and 2035 in the US and the anticipated rise in average maternal heat exposure across different regions as a result of global climate change, the researchers concluded that as many as 7000 additional cases of CHD will present during that decade.
The greatest percentage increases in the number of newborns with CHD will occur in the Midwest, followed by the Northeast and South.
“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 senior author Dr Shao Lin, professor in the School of Public Health at University of Albany, New York, in a prepared statement.
“It is important for clinicians to counsel pregnant women and those planning to become pregnant on the importance of avoiding extreme heat, particularly three to eight weeks post conception, the critical period of pregnancy.”