For ladies who have already had children?

I'm 31 weeks pregnant...this is my first child and I'm 21 years old. What I was wondering is when you have the baby and work out and lose weight and all that...do you have hanging skin from your tummy? Like the people who get that gastric byp surgery I saw a show they lose lots of weight but then have like skin hanging from their tummys...So I was just wondering if that happens or if you can get your stomach back to looking like the prepregnancy stomach?