Kelly says that although she turned 30 this year she still doesn't feel 'broody', but is very excited about her friend and former Destiny's Child band mate's new arrival.
In an interview with British Marie Claire magazine, the Down For Whatever singer said: 'I'm so excited for her. I will babysit and change a diaper or two, and then give it back.
'I do want kids, but every time I think about a little person growing inside of me and getting bigger and bigger and then having to come out.
'A watermelon coming out of something the size of a lemon is insane to me.'