Pregnant women are receiving more high-tech imaging exams, exposing their babies to higher doses of radiation than a decade ago, a study said on Tuesday.

Reuters reports that while the levels of radiation exposure are low, they carry a slight risk of harm to the developing fetus, said study author Elizabeth Lazarus, a professor of diagnostic imaging at the Warren Alpert School of Medicine at Brown University in Providence, Rhode Island.

A review of 5,235 imaging examinations performed on pregnant women at Brown from 1997 to 2006 found the number of those exams rose 121 percent. The exams included computed tomography (CT), nuclear medicine and plain film X-rays.

An abdominal ultrasound, a routine exam performed during pregnancy, does not expose the patient to ionizing radiation, which can cause cell damage.

CT exams, which deliver more radiation than other procedures, saw the greatest increase in use, rising by about 25 percent a year. Use of X-rays increased 7 percent a year, and nuclear medical exams rose by 12 percent annually.

CT scans are used in pregnancy only to detect potentially life-threatening conditions such as bleeding in the brain, blood clots in the lungs or appendicitis.

Researchers estimated the average fetal radiation exposure for CT was 0.69 rads, compared to 0.04 rads for nuclear tests and 0.0015 rads for X-rays. The data were released at a meeting of the Radiological Society of North America in Chicago.

"A patient being recommended for a test like this should talk to their doctor to find out if there are any alternative tests or if there is any harm waiting," Lazarus said in an interview.

"But if one of these tests is needed, we would not discourage any patients from undergoing one, because making a diagnosis could also be life-saving."

(Reporting by Susan Kelly, editing by Philip Barbara)