I wondered this, too. However on last night's episode, when she was talking to John re. their break-up, she grabbed her stomach and said "ooooh" and he said "What's wrong? Is it the baby?" and she said "No, it's not the baby, it's me".T1130 said:How come Gabrielle doesn`t act or look pregnant?
So, they haven't entirely forgotten it as it was briefly touched on. I just think they're more concerned w/Gabrielle finding out that John's love for her wasn't as deep as she thought it was.