My grandma was 4ft11 and her babies were all born at home with no tearing and no prolapses. 11 babies in all. And she had one that was 11lb and one that was 13lb, the rest were all at tiny 9lb

It's simply not true that women who are small can't give birth. Pelvises OPEN to allow babies out. And being small isn't a cause of a prolapse after birth, pelvic floor damage is the reason and that can be prevented with pelvic floor excercises during pregnancy in most cases.

You can't accurately predict whether or not a baby will fit through a pelvis until it's TRYING to get through it, and the pelvis is TRYING to open up.