I never did more than walk while PG. Maybe that is part of the reason I gained almost 50 lbs, twice (and 38 the middle one!).
I would have had what was classified as abdominal diastasis. There are PP tests that they have to be so far apart to qualify. Then there are modified ab routines to help it as opposed to making it worse.
I work out pretty intensely now. They have went back together, but I can still put a finger between them if I try. For me, the 3-4" above my belly button is where I feel it the most. For it to get any better from wherre I am now, would require surgery (and my youngest is 2.5 years).