The risk of being born with a major heart defect is 36% higher in babies who were conceived after assisted reproductive technologies, such as in vitro fertilization (IVF), according to the results of a very large study published in the European Heart Magazine today.
Researchers say the finding is important since congenital heart defects are the most common form of birth defects and some of them are associated with life-threatening complications.
The study also shows that the increased risk is especially associated with multiple births, which are more common in assisted reproduction.
The study was led by Professor Ulla-Britt Wennerholm from the University of Gothenburg in Sweden. She said: “Previous research shows that there are increased risks for babies conceived with the help of assisted reproductive technology. These include premature birth and low birth weight. We wanted to investigate whether the risk of heart defects was higher for babies born after assisted reproduction.”
The research included all children born alive in Denmark between 1994 and 2014, all children born in Finland between 1990 and 2014, those born in Norway between 1984 and 2015, and those born in Sweden from 1987 to 2015; more than 7.7 million in total.
The researchers compared data on babies born through assisted reproduction, including IVF, intracytoplasmic sperm injection (ICSI), and embryo freezing, with data on babies conceived naturally.
They assessed how many live-born children in each group were diagnosed with a major heart defect or a severe heart defect, either in utero or in the first year of life. They took into account other factors that may increase the risk of congenital heart defects, such as the year of the child’s birth, the country of birth, the mother’s age at the time of delivery, whether the mother smoked during pregnancy, or whether the mother had diabetes or heart defects.
This showed that heart defects were about 36% more common in babies born after assisted reproduction, compared to babies conceived without such treatment (absolute risk 1.84% versus 1.15%). This risk was similar regardless of the type of assisted reproduction used (IVF or ICSI, fresh or frozen embryos). However, the risk was higher in multiple births after assisted reproduction compared to single births after assisted reproduction (2.47% vs. 1.62%).
Professor Wennerholm said: “We already know that babies born after assisted reproductive technology have an increased risk of birth defects overall; however, we have found an increased risk also in congenital heart defects, the most common major birth defect.
“The fact that the risk of heart defects is similar regardless of the type of assisted reproduction used may indicate that there is some common factor underlying infertility in parents and congenital heart disease in their babies.
“Congenital heart defects can be extremely serious and require specialized surgery when babies are very young, so knowing which babies are most at risk can help us diagnose heart defects as early as possible and ensure they are given the right care and treatment.” More and more people are conceiving with the help of assisted reproductive technology, so we could expect to see increases in cases of congenital heart defects around the world.
In an accompanying editorial, Dr. Nathalie Auger, of the University of Montreal Hospital Research Center in Canada, and colleagues said: “Assisted reproductive technology is a popular intervention in reproductive medicine, and these procedures represent the 2% to 8% of births, depending on the country Although the majority of newborns born after assisted reproductive technology are healthy, these procedures are not without risks.
“In one of the largest studies to date, researchers found that assisted reproductive technology was associated with the risk of major heart defects diagnosed before birth or before one year of age.
“Patients who use assisted reproductive technology tend to differ from the general population. These patients may have underlying morbidities that affect both fertility and the risk of heart defects.”