And it's implausible that a six month old fetus could survive without intensive hospital care, but logic has never been this show's strong suit.
If the baby is dead, that means the story is stuck with a newborn ghost baby character indefinitely, which seems clumsy and not very useful to the show going forward. A live baby will pose problems that can generate story (how are they going to feed him?) and he can grow into a toddler at least, and become a factor onscreen. A newborn baby may as well just be a prop.