NEW YORK (Reuters Health) – The number of newborns in Europe affected by heart defects appears to have fallen in recent years, but it’s not clear why, says a new study.
A team of European Union researchers analyzing millions of birth records found that the number of European babies born with heart defects fell from around seven in every thousand births in 2004 to around six per thousand by 2007- a drop of around 4% each year.
While any drop in the numbers of babies born with birth defects is good news, experts noted that the decline is a modest one and the researchers can only speculate about the reasons for it.
But Dr. Joe Simpson at the New York-based March of Dimes foundation, a non-profit organization that works to improve babies’ health, said there is cause “for a high level of skepticism.”
“It would be lovely if… true,” Dr. Simpson told Reuters Health, but given the lack of explanation for the change, “whether it persists over time remains unclear.”
For the new study, a team led by Dr. Babak Khoshnood at the National Institute for Health and Medical Research (INSERM), in Paris, France, looked at data on congenital heart defects collected in 16 mostly western-European countries between 1990 and 2007.
They found 47,000 cases of congenital heart disease among more than seven million births.
According to the report, published in the Journal of Pediatrics, rates of the most severe forms – such as hypoplastic left heart syndrome — have held steady at around five per 10,000 births since 1990.
But less severe conditions decreased from roughly 50 cases to 40 cases per 10,000 births between 2004 and 2007. For a country like France, with around 780,000 births a year, that means about 780 fewer babies born with heart problems every year.
Dr. Khoshnood speculates that increased folic acid intake by European women is a possible cause of the decline in defects. But, “we don’t have the data to know for sure,” he added.
Dr. Sunil Malhotra, a surgeon specializing in congenital defects at New York University, points out, however, “Folic acid has been a part of prenatal care in the U.S. for the better part of a decade, but there hasn’t been a similar decrease (in heart defects) here.”
According to the American Heart Association, the causes of congenital heart defects are still unknown. So researchers can only speculate about what could be causing the European decline.
Dr. Simpson and Dr. Malhotra noted further limits to the new study
Methods to diagnose birth defects have changed during the last 20 years, said Dr. Simpson. And with babies leaving the hospital within a day of being born, there is less time to spot heart defects.
“I was not overwhelmed by the strength of the data,” Dr. Malhotra added. The study draws on data from a lot of different country registries that each collect and store data in a different way, and that data can often be incomplete, he said.
J Pediatrics 2012.