I've heard a lot of "experts" say that nothing works, but that they lighten over time. My red stretch marks turned a silvery color. My husband doesn't mind them because I got them bearing his children.

Sagging skin - I don't know. A friend of mine tried and tried and tried with lots of exercise and finally got a tummy tuck when she decided she was done having kids. They make a cut around your pelvic area, tug the skin down and cut off the excess, then they give you a fake bellybutton because the old one is gone. I'd rather have the sagging skin.