Humans actually have lots of problems giving birth, primarily because of our large brains, and its only been with medical science that giving birth became 'easy'. It's still like 18 hours of screaming agony but at least there's little chance now of the mother or infant dying during the process. In the old days before science it wasn't some ungodly 1 in 5 chance of a successful birth, but it was still around 2 in 3 or 1 in 2.