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CT tests during pregnancy do not boost childhood cancer risk: study

Pregnant women who undergo CT or nuclear imaging tests during pregnancy do not appear to have babies at higher risk of developing childhood cancer, says a new study led by St. Michael’s Hospital physician and Institute for Clinical and Evaluative Sciences (ICES) researcher Dr. Joel Ray.

Toronto, September 8, 2010

Dr. Joel Ray Dr. Joel Ray

The study of 1.8 million mother-child pairs in Ontario identified 5,590 women who had a major radiodiagnostic test (CT or nuclear imaging) during pregnancy, now performed in about 1 in 160 pregnancies.

Researchers found while the probability of babies developing childhood cancer was less than one in 1000, the rate of diagnosed childhood cancer was actually lower in the children exposed to a major radiodiagnostic test.

“Cancer is a leading cause of hospitalization and death among children 14 and younger yet, we observed no higher risk to the child after CT or nuclear imaging during pregnancy,” Dr. Ray said, “Our findings signal that, when necessary, major radiodiagnostic testing during pregnancy should be carried out, along with brief counseling of the mother.”

“These imaging tests may be especially important during pregnancy, when major illnesses like lung clots or appendicitis can be missed,” he added. “Delaying the diagnosis of such conditions may postpone therapy, in turn, jeopardizing both mother and child,” Dr. Ray said.

The study "Major Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: A Population-Based Cohort Study in Ontario" is in the September 7, 2010 issue Open-Access journal PLoS Medicine.

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