I know plenty of women who have had babies and have no stretch marks and have flat tummies. My friend has three kids and after her third one, was wearing her old slim-fitting nonmaternity dress 5 days after the delivery. Plenty of women don't need to do any exercise to regain their pre-preg bodies. And some can bust their behinds for the rest of their lives and never come close.
3b (with 3c tendencies) on modified CG