Doctors Overestimate Radiation Risk to Fetus
Survey Shows Some Would Recommend Pregnancy Termination
May 18, 2004 -- The risk of having a child born with a major birth defect is much lower than many doctors think for women who undergo abdominal X-rays or CT scans during early pregnancy, and doctors may be giving poor advice to their pregnant patients as a result, new research suggests.
Investigators from the University of Toronto's Hospital for Sick Children surveyed 273 family doctors and obstetricians in Ontario and found that about a third overestimated the risk of major birth defects from a simple abdominal X-ray and about half overestimated the risk from a CT scan.
The doctors were informed about the1%-3% risk for major birth defects associated with these procedures and were asked whether they would recommend that a woman undergo an abortion because of radiation exposure from these procedures.
One percent said they would recommend an abortion to a woman who had abdominal X-rays and 6% said they would recommend an abortion following an abdominal CT scan.
A typical abdominal X-ray or abdominal CT scan contains radiation levels that are generally considered to pose little risk of permanent injury to a developing fetus.
"A big misperception exists among physicians about the risk to a fetus from diagnostic X-rays," study researcher Gideon Koren, MD, tells WebMD. "With the levels of radiation used today, there is little risk of a diagnostic procedure endangering the fetus."
Cancer Risk a Greater Concern
Fred Mettler, MD, a member of the International Commission on Radiation Protection and the U.S. representative to the U.N. on radiation effects, tells WebMD getting five or 10 CT scans during pregnancy could result in enough exposure to radiation where there might be a risk for developmental problems in the fetus.
A greater concern to most radiation experts is the long-term cancer risk to children and fetuses exposed to radiation, he says. Radiation-related cancer risk is generally believed to be three times higher for children and fetuses than for adults.
"Many people believe that a child's risk of leukemia doubles at fairly low levels of exposure," he says. "But you are still talking about a risk of one in 2,000, and that is still pretty small."
Low Birth Weight
Several recent studies suggest that dental X-rays conducted during pregnancy can increase a woman's risk of delivering a low-birth-weight baby. Koren says the studies are far from conclusive and may unnecessarily scare women away from dental checkups at the time when they need them most.
A woman's risk of developing gingivitis and other gum problems increases during pregnancy, and gum disease is also believed to increase the risk for early delivery.
"It is important that pregnant women get the care they need, and that they are given the right information about radiation risk," Koren says. "The message to physicians is please, please get the information you need to counsel patients."