Assisted reproductive technology is associated with an increased risk of certain types of birth defects, according to a report from the Centers for Disease Control and Prevention.
The findings, based on data from the ongoing National Birth Defects Prevention Study—a population-based case-control study of birth defects—indicate that infants conceived using ART are twice as likely to be born with certain types of heart defects and with cleft lip (with or without cleft palate), and are more than four times as likely to have certain gastrointestinal defects, compared with those conceived naturally.
The investigators noted, however, that the underlying biologic mechanism by which ART might affect development remains unclear and that without further study, practical application of the results is limited.
The report, published in Human Reproduction (doi:10.1093/humrep/den387
Those considering ART should be informed of the risks involved, they urged.
The investigators compared outcomes in 281 babies conceived using in vitro fertilization (IVF) or intracytoplasmic sperm injection and 14,095 conceived without ART delivered between October 1997 and December 2003.
After controlling for maternal race and ethnicity, age, smoking, and parity, they found that among singleton births, the use of ART was associated with septal heart defects (adjusted odds ratio, 2.1), cleft lip with or without cleft palate (adjusted OR, 2.4), esophageal atresia (adjusted OR, 4.5), and anorectal atresia (adjusted OR, 3.7). Among multiple births, none of the more than 30 defects studied was significantly associated with ART.
The authors acknowledged that underlying infertility, small numbers, and chance may have played a role in the increased risk of birth defects found in the study.
Indeed, “this study suffers from the same significant deficiencies as many others looking at IVF outcomes,” Dr. Elizabeth Ginsburg, president of the Society for Assisted Reproductive Technology (SART), said in an interview. That is, rather than comparing two similar populations, this study compares babies of infertile women undergoing ART with those of fertile women. As a result, no conclusions can be made about why the incidence of birth defects is higher in those undergoing ART, she explained.
“I don't think the study changes what we have been telling our patients for some time, which is that there may be a higher risk of birth defects or other adverse outcomes in babies born from IVF. Whether these findings are due to the fact that there is something different about couples with infertility who require IVF to conceive or something related to the treatment itself, we don't know,” she said, adding that patients have the right to be informed, regardless.