The picture by the right was taken about a month now, while the one by the left was taken about a week now on a movie set. This is just an assumption while we wait for the main news (if it’s true). Remember the actress and mother of three talked about having a 4th child when people were bashing her for have the 3rd child not long after she had the 2nd.
The only thing that can explain the left picture if she is not pregnant is one thing ‘Waist Clincher’.