-y is a common baby-talk suffix appended to words such as pig (to make piggy), kitten (to make kitty), etc. As babe used to be a common word for infants and young children, I thought it would be likely that baby is a hypocoristic form of babe, originating from baby-talk. However, I have no way to back up this hypothesis, and am wondering if someone else knows how to prove or disprove it.