You are not required to declare that you are pregnant but if you wish to, there is a form.
This is totally voluntary.
If you are pregnant, you have the option to declare your pregnancy and/or request reassignment. Workers who have declared pregnancy must meet additional dosimetry requirements.
The embryo-fetus is known to be more sensitive to radiation than adults due to the rapid division rate of
developing cells. Radiation doses can increase the chances that the child will experience slower growth or
mental development, or develop childhood cancer.