The condition of being pregnant is not a blacklist tag because tags in that category generally elicit at least a questionable rating. Post #200517 and post #189920 for example are tagged safe. Moving pregnant from the physical_attributes to the blacklist category would imply it should not be tagged safe (although I will note that some tags in that category don't by themselves require such a rating, navel for example but I lumped it in with anatomy as most such tags belong there).

It there is a general consensus to move pregnant to the blacklist category?