According to the NCRP, there is cause for concern if a pregnant woman receives a dose in excess of ______ to the uterus.

The National Council on Radiation Protection and Measurements (NCRP) establishes guidelines regarding exposure limits to ensure the safety of individuals, especially vulnerable populations such as pregnant women and their unborn children. The threshold of 25 Gy-t to the uterus is significant because it is recognized as the level at which potential detrimental effects on the developing fetus can occur.

Exceeding this dose can lead to risks such as teratogenic effects, developmental issues, or an increased probability of cancer later in life for the child. The NCRP maintains this guideline to promote caution and to prevent excessive radiation exposure during pregnancy, which is a critical period for fetal development.

Lower thresholds, such as those in the other options, are also important, but they represent levels where immediate concern might not warrant the same level of alarm as 25 Gy-t does. By establishing 25 Gy-t as the threshold, the NCRP prioritizes the reproductive health of both the mother and the fetus, ensuring that safety guidelines are in place for medical practices involving radiation.