My mom (a CNM) once told me about the "rule of 5's" meaning ring size 5 or under, height 5' or under and shoe size 5 or under might mean a really small pelvis. Of course, I'm 5' tall, wear a size 5 shoe and a 3.75 ring. So I was a little worried. Turns out I had two preemies, a 5 pound 4 ounce one and a 4 pound 1 ounce one, so I never got to test the "rule" and see if it was true! They both were vaginal though, no tears.