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 study investigators noted, however, that the underlying biologic mechanism by which ART might affect development remains unclear and that without further study, the “practical application of our results is limited.”
The CDC report, published in Human Reproduction (doi:10.1093/humrep/den387), states that the overall risk of birth defects associated with ART is low, but important for consideration by prospective parents considering assisted conception.
For example, cleft lip with or without cleft palate affects about 1 in 950 births in the United States; among those conceived using ART, cleft lip with or without cleft palate affects about 1 in 425 births, lead author Jennita Reefhuis, Ph.D., an epidemiologist at the CDC's National Center on Birth Defects and Developmental Disabilities, and her colleagues reported.
Those considering ART should be informed of the potential risks involved, the authors urged.
For their study, 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, and as a result no conclusions can be made about why the incidence of birth defects is higher among 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.
In fact, an informed consent form was recently developed by SART to help its members ensure that all SART clinics have the information they need to apprise patients of the potential risks of ART treatments, she said.
The comprehensive 20-page form, introduced Nov. 11 at the annual meeting of the American Society for Reproductive Medicine, provides an overview and explanation of ART services and how they are performed, as well as a detailed explanation of potential risks to both the patient and any resulting children.
Currently about 1% of infants in the United States are conceived using ART, and the number is expected to increase. Between 1996 and 2004, the number of infants born following ART doubled, according to the CDC report.
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