) I don't have a personal experience, but a friend of mine had 2 children, both in her early 20s (3 years apart) after
she had her breasts
enlarged and I know for sure she did not remove the implants
during that time. The pregnancies did not "ruin" the breasts and went back to their size afterwards. I don't know about stretch marks, didn't see them ;) She was even breastfeeding both kids and seemed fine. Sorry, that's all of my limited knowledge about the issue!