The maximum allowable radiation dose to the fetus for occupationally exposed pregnant women during the entire gestation period is 0.5 rem (5 mSv). This limit is set to minimize the risk of teratogenic effects, growth retardation, and other radiation-induced fetal damage. Regulatory agencies such as the NRC and the ICRP recommend this dose to ensure fetal safety while allowing essential occupational exposure. Keeping exposure below 0.5 rem helps protect the developing fetus especially during critical periods of organogenesis and central nervous system development.

Reference: Radiation Safety in Medical Radiography, 7th Edition.