greyskull,
Xenomorph,
16 years ago
It's possible that the alien eats the babies. However, I suspect that as a host for new xenomorphs I suspect that it rejects the idea. If we look at the biology of the xenomorphs they need a host that can accomodate the xeno embryo for a specific gestation period -- from what I've seen and read it's on the order of 6 to 8 hours. Once the gestation period is complete the new xeno must burst out of the chest. During this gestation period the embryo has to grow - and grow quickly which means it needs a lot of energy to create new skin, bones, armor, teeth, etc. Clearly it doesn't do so by eating its host from the inside (the hosts seen in the movies - from Kane all the way to the father/son in AVPR -- all just "wake up" and then die when the xeno bursts out of their chests) since doing so would probably kill the host during the gestation period (although we do know that the xenos can gestate in corpses for a least a little while since the PredAlien burst out of a Predator corpse).
Given all of the above it seems reasonable to assume that the xeno requires a host of some minimal size to properly gestate. I suspect that the PredAlien looked at the babies in the nursery and decided either that they were unsuitable as hosts and moved on or decided that they were unsuitable as hosts and ate them. My personal feeling is, given that the xenos are ostensibly consumed with an extremely strong drive to infect other hosts to create more xenos then the PredAlien simply moved on and decided that the babies were of no interest. Did it eat them? Given that I don't recall seeing any xeno in any of the films eat anything I suspect not.
Just my .02