I used to be quite vain about my belly button, really, in hindsight.
With DS1, it was a bit out of shape but would probably gone back.
With DTDs, it stretched, went inside out and stretched some more. I have stretch marks inside my belly button. I thought I was never going to have a proper belly button again. On Woman's Hour, some doctor said that if your tummy does not go back after a year, that is it! I was gutted
.
However, after I started doing ballet and contemporary dance, all the standing up straight and holding in bore fruit and I got some sort of semblance of belly button back (albeit not for public display).