An increase in the number of congenital heart defects is a possible consequence of global warming. Environmental doctors recently published the results of a major study in the journal JAHA.
How are warming and congenital heart defects linked?
The cause of congenital heart defects has not yet been identified. Possible factors include excessively high air temperatures. Heat has a teratogenic effect, which affects not only animals, but also humans.
The teratogenic effect is a violation of embryonic development due to the action of aggressive factors.
In recent years, 2 studies indicate a possible increase in heart defects after periods of heat in spring or summer. Scientists from the University of Montreal reported that the prevalence of heart defects increased from 878.9 to 979.5 per 100,000 births. Especially at summer temperatures above 30 ° C, 2–8 weeks of gestation has the highest number of cases.
Other scientists recently came to similar conclusions in the analysis of the National study on the prevention of birth defects in the United States. More heart defects were observed in newborns on hot days in early pregnancy. From 3 to 11 days of heat in the summer in early pregnancy increased the risk of ventricular septal defects by 2.17-3.24 times.
The days of extreme heat in spring were associated with an increase in the number of defects of the interventricular septum by 23-78%. Experts compared their data on climate change scenarios for 8 US regions for the period from 2025 to 2035.
NASA and the Space Research Institute have predicted the highest relative growth of hot days in midwestern states during the summer months. The population of the south and southwest is burdened with additional periods of intense heat in the spring.
In the least favorable of the 3 scenarios, there may be about 7000 additional births with heart failure in 8 regions over 11 years. For comparison, about 40,000 children with heart defects (325 million inhabitants) are born annually in the country.
According to scientists, the worst hit will be in the south and northwest, and then the midwest. West, say California, spared the extra heat waves.
Researchers advise pregnant women to avoid extreme heat in early pregnancy. Especially during pregnancy from 3 to 8 weeks, they should not spend too much time outdoors on hot days.
In which countries is climate change observed?
More than 30% of the world's population currently lives in places where temperature and humidity are harmful to humans for at least 20 days a year. According to estimates in Natural Climate Change, this proportion will increase to 48-74% by 2100. Deadly heat waves, like in Chicago, Paris or Moscow, are becoming more common.
In July 1995, 740 people died in Chicago after a fever of over 40 degrees Celsius for 5 days. Only during the heatwave of 2003, 4,870 people died in Paris, and in Europe it reached 70,000. In the summer of 2010, according to official statistics in Moscow, 10,860 people died from overheating. In recent years, there have been more heat waves in New York, Washington, Los Angeles, Chicago and Toronto.
Air quality has also deteriorated in many countries. According to the report, PM2.5 concentration in particulate matter has increased by 11.2% since 1990. Today, about 71% of the 2971 cities monitored by WHO regularly exceed recommended limits.
The number of people exposed to heat waves increased by 125 million, according to researchers. In 2018, 175 million people were affected.
The consequences range from heat stress or stroke to exacerbation of pre-existing heart failure.
What to do in case of excessive heat?
Pregnant women and patients at risk are not recommended to go out in the open sun. It is necessary to consume a sufficient amount of liquid (at least 1.5 liters of liquid) and often take a shower.
If you experience dizziness or headache, you should seek medical help. A timely visit to a doctor helps to prevent the possible consequences of overheating.
