It's not uncommon. Apparently women have to be careful with certain excessive or weight lifting as their womb can literally fall out. Apparently when my Nan was working at the hospitals she heard of a few cases and even personally knew a women to which it had happened. So when my misses tries to lift heavy things, I tend to do it for her. Would be freaky if it happened to her. Plus I think I was told that it doesn't always happen, only in those women who have weaker then normal muscles or tendons or whatever it's called that holds the womb in place.