I don't believe that there is only one standard of morality, or that any action will invariably be morally correct. It all depends on your interpretation or which values of morality you hold the highest. In fact, I'm not even sure if "morally correct" is the right question to even be asking here. The fact that one action might be the lesser of two evils does not necessarily equate to right or wrong.
If you believe in "greatest good for the greatest number", perhaps suffocating the baby so that others might live might appear to you as the best response. However, if you believe taking a human life is always morally wrong, then you would presumably never support killing the child. I think morality is always subjective, as it's inevitably in reference to some kind of value and how that affects your personal hierarchy of interests or priorities.