For the first time, a large study suggests there is a higher rate of childhood cancer among test-tube babies, but researchers say the reason probably has nothing to do with how the children were conceived.
More likely, the reason is related to the genetics of the parents who turned to in vitro fertilization because of infertility, the study's Swedish authors and other experts say. Also, test-tube infants often are born prematurely and have breathing problems at birth — traits linked in other studies with increased cancer risks.
Still, cancer in these children is rare, despite any elevated risks.
"It's rather reassuring," said Dr. Bengt Kallen, the study's lead author and a researcher at the University of Lund. The risk "is so small that it can't matter much for the individual parents or parents-to-be."
The study examined Swedish children conceived by IVF, in which eggs are fertilized with sperm in a lab dish and then implanted into the womb.
Dr. Tommaso Falcone, the Cleveland Clinic's obstetrics and gynecology chief, said it's uncertain whether similar results would be found in the more racially diverse United States. About 57,000 infants are born after IVF each year in the U.S. — roughly 1 percent of all births
The results of the new study were published online today in Pediatrics. More than 2.4 million births in Sweden between 1982 and 2005 were analyzed, including those of almost 27,000 IVF babies, along with cancer data in children tracked for up to 19 years.
Overall, 53 IVF children developed cancer, compared with 38 that would be expected to in other children of the same age, about a 40 percent increased risk. Leukemia and brain cancers were among the most common.