The rate of congenital heart defects is higher in newborns conceived using assisted reproductive technologies (ART) than in newborns conceived without assistance. This finding comes from a population-based cohort study led by Dr. Nona Sargisian, a gynecologist at the University of Gothenburg, Sweden, and colleagues, which was published in the European Heart Journal.
The researchers analyzed more than 7 million results of all live-born children in Denmark, Finland, Sweden, and Norway between 1984 and 2015. They found that congenital heart defects occurred more frequently in the ART newborn group (1.85%) than in naturally conceived newborns (1.15%).
The study also revealed that the risk for congenital heart defects in multiple births is higher than in single births, with and without the use of ART. However, the result that congenital heart defects occur more often in ART newborns remained significant when comparing single births from both groups (1.62% vs 1.11%).
Relatively Low Prevalence
Barbara Sonntag, MD, PhD, a gynecologist at Amedes Fertility Center in Hamburg, Germany, referred to a “clinically relevant risk increase” with a relatively low prevalence of the condition.
“When 1000 children are born, an abnormality occurs in 18 children after ART, compared with 11 children born after natural conception,” she told the Science Media Center.
Dr. Sonntag emphasized that the risk is particularly increased by a multiple pregnancy. A statement about causality is not possible based on the study, but multiple pregnancies are generally associated with increased risks during pregnancy and for the children.
The large and robust dataset confirms long-known findings, said Georg Griesinger, MD, PhD, medical director of the fertility centers of the University Medical Center Schleswig-Holstein in Lübeck and Manhagen, Germany.
The key figures can be found in single births, he explained. “Among single births conceived by ART, the rate of severe congenital heart defects was 1.62% compared with 1.11% in spontaneously conceived single births, an increase in risk by 1.19 times. For severe heart defects, the rate was 0.31% in ART single births, compared with 0.25% in spontaneously conceived single births.”
The increased risks are consistent with existing literature. Therefore, the current study does not reveal any new risk signals, said Dr. Griesinger.
Single Embryo Transfer
The “risks are small but present,” according to Michael von Wolff, MD, head of gynecological endocrinology and reproductive medicine at Bern University Hospital in Switzerland. “Therefore, ART therapy should only be carried out after exhausting conservative treatments,” he recommended. For example, ovarian stimulation with low-dose hormone preparations could be an option.
Dr. Griesinger pointed out that, in absolute numbers, all maternal and fetal or neonatal risks are significantly increased in twins and higher-order multiples, compared with the estimated risk association within the actual ART treatment.
“For this reason, reproductive medicine specialists have been advocating for single-embryo transfer for years to promote the occurrence of single pregnancies through ART,” said Dr. Griesinger.
The study “emphasizes the importance of single embryo transfer to avoid the higher risks associated with multiple pregnancies,” according to Rocío Núñez Calonge, PhD, scientific director of the International Reproduction Unit in Alicante, Spain.
Dr. Sonntag also sees a “strong additional call to avoid multiple pregnancies through a predominant strategy of single-embryo transfer in the data. The increased rate of childhood birth defects is already part of the information provided before assisted reproduction.”
This story was translated from the Medscape German edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.