Nope! An alien is a member of a species from another planet! So, since the baby was human, which is an Earth species, it isn't an alien, even if it was born in space.
No. The baby is 由 definition a human due to the fact that the mother is human. However! The baby can be considered a foreigner, 或者 "alien", depending on who owned the spaceship the baby was born on at the time. If owned 由 the Americans, the baby would be considered "alien" to other nations. If born on a Russian spaceship, the child would probably be considered as a Russian citizen and be an "alien" to the U.S.A.
That of course would be my judgement on the situation. The baby would also be stranded up until the 识骨寻踪 fully develop in its body, a process that takes years.