Actually, they do! They do somersaults and all that crap. With the cord around the neck - this isn't necessarily a problem before birth, unless it gets compressed for some reason, as babies don't breathe in the womb, they get oxygen from mum's blood/placenta. Where this cow is so wrong is that a uterus has plenty of room for a fetus in it and stretches according to the size of the baby when it gets big enough to create a bump. If a bump looks bigger on the outside, it's not because the uterus is bigger than someone else's at the same stage of pregnancy, it's because there are LAYERS of disgusting blubber around it.    Edit for added sauce: http://www.whattoexpect.com/pregnancy/fetal-movement