All flesh will be renewed, not just all human flesh.
Does the fact that the Bible doesn't address what happens to dead human babies and fetuses mean that they don't get an afterlife? No, that would be presumptuous. More likely, it isn't mentioned because, as with animals, babies won't ever read the Bible, so there is no need for it to mention this.
armothe,
God permitted some Old Testament Jews to eat members of other species. He also allowed them to take as slaves members of other races. If the fact that God allowed people to use animals for physical ends means that animals have no eternal consciousness (and therefore get no recompense for the incredible suffering many go through while alive), does this also mean that the people they were allowed to use for physical ends also have no eternal consciousness? I don't think it's logical to suppose that for an individual to have a physical purpose prevents them from having a spiritual existence.
More thoughts:
Maybe animals can sin; maybe they can't. If they can't choose evil, they can't choose good either, in which case they're neutral. Neutral is still better than evil, which we humans are. I don't see why the suffering of animals in that case should never be recompensed in Heaven if it is for those like us, who don't deserve it. That belief that animals' experiences have no importance is not founded in the Bible: Proverbs 10, The righteous man regardeth the life of his beast: but the tender mercies of the wicked are cruel. It is, however, a belief consistent with cultural norms, and people have often tried to defend selfish (sinful) cultural norms and prejudicial lack of compassion with the Bible, slavery again being an extreme example. History teaches us how vulnerable the human race is to cultural conditioning and its consequent subjectivity in reading God's Word. The common belief that the suffering of animals doesn't matter (but should be prevented when it makes us feel better - there's that selfishness again) which I myself came close to buying into (society en mass has a way of wearing you down) is another of the numerous cases of experience and desensitisation trumping both reason and empathy. It's just human nature, and we all know about that.