Carcinogenic risks of prenatal ionizing radiation.

The risk of cancer in offspring who have been exposed to diagnostic X-ray procedures while in utero has been debated for 55 years. High doses at high dose rates to the embryo or fetus (e.g. >0.5 Gy) increase the risk of cancer. This has been demonstrated in human epidemiology studies as well as in mammalian animal studies. Most pregnant women exposed to diagnostic X-ray procedures or the diagnostic use of radionuclides receive doses to the embryo or fetus <0.1 Gy. The risk of cancer in offspring exposed in utero at a low dose such as <0.1 Gy is controversial and has not been determined.