Fear of the unknown: ionizing radiation exposure during pregnancy.

Ionizing radiation during pregnancy can negatively impact a fetus. In light of the Fukushima nuclear plant disaster in Japan, we discuss existing knowledge on the health effects of radiation and preventive measures for pregnant women. Overall, the risk of exposure to radiation is limited but severe defects can result from fetal radiation exposure >100 mGy equivalent to 10 rad (>1000 chest x-rays). While such high-level exposure rarely occurs during single medical diagnostic procedures, caution should be exercised for pregnant women. As a protective public health measure in light of a disaster, evacuation, shielding, and elimination of ingested radioactive isotopes should all be considered. Detailed radiation reports with health effects and precautionary measures should be available for a population exposed to more than background radiation.