The aparent uniform expansion of the belly in the manner of a pregnant woman, not caused by excess natural body mass.

If this is due to the presence of liquid or gass pushing outward, use inflation as well.
If this is due to a solid object pushing out the WHOLE belly, use stomach_bulge as well.
If this is due to a solid object that does not visibly expand the whole abdomen, use stomach bulge INSTEAD of abdomen_swell
abdomen swell