Maternal exposure to air pollution may increase the risk of heart defects in an unborn baby, according to new research out of China, which suggests risks in the three months leading up to pregnancy are just as high as during the mother’s first trimester.
“It means that reducing exposure to air pollution in the three months before conception and in the first trimester period is equally important in preventing congenital heart disease in the offspring,” said Dr. Hammin Liu, co-lead author of the study published Monday in the American Heart Association’s journal Circulation. Liu is President of West China Second University Hospital and Professor of Pediatrics at Sichuan University in Chengdu, China.
Congenital heart defects are the most common type of birth defect and the leading cause of infant mortality worldwide. More than 80% of heart defects have no known cause, but previous research suggests that environmental exposure may play a role.
Studies examining the association between maternal exposure to particulate matter (PM2.5) — tiny pollutant particles such as smoke or dust — and heart defects were limited in size or location, or were conducted in countries with lower pollution levels than Germany China has levels of particulate matter, which are 6.5 times higher than the World Health Organization air quality guidelines.
Overall, the risk of giving birth to a baby with a heart defect increased by 2% for every 10 micrograms per cubic meter increase in maternal exposure to PM2.5. The adverse effects of exposure to air pollution were more pronounced during the period before conception than during the mother’s first trimester.
While previous research has shown that maternal exposure to air pollution in the first trimester can be dangerous for the unborn child, this is the first study to provide evidence that the danger could start much earlier, said Dr. Jonathan Newman, Eugene Braunwald Assistant Professor of Medicine at New York University Grossman School of Medicine in New York City.
“This is a new observation that we really didn’t have a lot of data to support,” said Newman, who wasn’t involved with the study. “It’s an important potential piece of the puzzle as we understand the negative health effects associated with air pollution.”
Whether these results would hold true in less polluted places like the United States is unknown. But Newman said it was an issue that should be investigated. “There really is no safe level of air pollution,” he said.
Women who are pregnant or thinking about becoming pregnant can reduce their risks in several ways, said Newman, who was lead author of a 2020 report in the Journal of the American College of Cardiology, which hosted a federal expert workshop on possible personal strategies summarized reducing exposure to air pollution to protect cardiovascular health.
One way is to use home air filters, he said. A 2020 AHA scientific statement recommends portable air purifiers, high-efficiency home filtration systems, closing home and car windows, and wearing face masks in areas of high exposure.
But “the larger context of risk management from any exposure is to reduce the overall risk of cardiovascular disease,” Newman said. In fact, a scientific statement from the AHA, also published in Circulation Monday, states that improving a woman’s heart health before she becomes pregnant could be key to reducing her risk of pregnancy-related complications and the mother’s long-term cardiovascular health and improve child.
“It is very important that women during pregnancy and the period before conception can seek and receive the necessary health evaluations and treatments, particularly for the management of risk factors such as high blood pressure or prediabetes,” Newman said. “Ensuring these risk factors are adequately addressed will also help reduce the health impacts of air pollution.”
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