Nov. 17, 2008 -- The CDC reports that certain birth defects -- including heart wall problems and cleft lip/palate -- may be two to four times more common among babies conceived with assisted reproductive technology (ART) than babies conceived naturally.
ART is becoming more common, but the CDC isn't making any recommendations about its use.
"Today, more than 1% of infants are conceived through ART and this number may continue to increase," CDC epidemiologist Jennita Reefhuis, PhD, says in a news release.
The chances of birth defects in a baby conceived through ART are "low," notes Reefhuis.
But she says "it is still important for parents who are considering using ART to think about all of the potential risks and benefits of this technology."
ART and Birth Defects Study
Reefhuis and colleagues reviewed data from mothers of about 13,500 babies born with birth defects and mothers of more than 5,000 babies without birth defects.
Those babies were born from October 1997-December 2003 in 10 states (Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Utah, and Texas).
About 1% of the babies without birth defects were conceived through ART, compared to 2.4% of the babies with birth defects, according to interviews with the mothers.
The following types of birth defects were more common among babies conceived through ART:
- Septal heart defects: Twice as common among babies conceived by ART
- Cleft lip and/or cleft palate: 2.4 times as common among babies conceived by ART
- Esophageal atresia (birth defect of the esophagus): 4.5 times more common among babies conceived by ART
- Anorectal atresia (birth defect in the anal/rectal area): 3.7 times more common among babies conceived by ART
Those findings, which take into account other risk factors, only applied to single births, not to twins, triplets, or other multiple births.
But the CDC points out that multiple births are associated with ART and with birth defects.
"Thus, ART might contribute to the risk of major birth defects both directly by increasing the risk of defects among singletons, and indirectly by increasing the occurrence of twinning which is a strong risk factor for many types of major birth defects," the study states.
The study doesn't prove that ART was to blame for the birth defects.
"Subfertile women might have a higher risk of having a child with a birth defect regardless of whether infertility treatments are used," write Reefhuis and colleagues.
The CDC also notes that birth defects are rare and that the findings in the new study need to be checked.
WebMD asked Elizabeth Ginsburg, MD, president of the Society for Assisted Reproductive Technology and medical director of assisted reproductive technologies at Brigham and Women's Hospital in Boston, about the new CDC report.
Ginsburg points out that the study included a small number of babies conceived through ART and that the study doesn't settle key questions about ART and birth defects.
"We've been counseling patients with infertility for a very long time that we don't know whether there's an increased risk of adverse outcomes for their baby," Ginsburg tells WebMD.
Ginsburg notes that some studies -- but not all -- link ART to poor outcomes for babies, but it's still not clear whether ART or infertility are to blame. "I think there are enough [studies] to say there may be something to it," but It's "unsettling" to have those issues unresolved.