If a baby is born dead, some of my mothers will try to eat the dead baby to "get rid of it". Probably as a protection for the other kits.
I've also seen newmothers try to kill and eat the babies because they are scared or threatened by the babies. (Where did THESE things come from! They have to go away!) Maternal hormones in a "first time" doe may not be strong enough for hours after kindling. One more reason to keep any eye on does when they kindle.
Any percieved threat (predator/noise/etc.) may cause a doe to get rid of the babies. Sad, but she does it for their own protection.