I had one after my 3rd, but didn't with my 4th and my 4th baby was a lot bigger again. I don't think the size of the baby has anything to do it with - retained placenta and PPH is just one of those things that can happen for no reason and while your risk of having another one is slightly higher than if you hadn't had one at all, there is no reason at ALL to rush to have a c-section birth just to avoid it. I think I would be staying firm on not having one, because there is still a risk of PPH with a c-section as well.