Omega males’ hips widen when they’re pregnant so they can give birth, and they never go back to normal afterwards. If an omega male’s given birth, you can tell just by looking at them. This makes their alphas very happy; their claim remains obvious during and after the pregnancy.
Very specific pet peeve of mine, I don't like how in some mpreg fanfictions sometimes they describe the omega's bump as being "very small bc he is a male.." COWARD!!!! GIVE HIM A BIG BUMP!!!!! LET IT BE KNOW HE IS CARRYING A CHILD!!!! NO OMEGA OF MINE WILL HAVE A TINY BUMP!!!