The knowledge of the nationality of New Zealand-born babies:
If both parents are New Zealand citizens/residents, the child is a New Zealand citizen
If one of the parents is a New Zealand citizen/resident, the child is a New Zealand citizen
If both parents are not New Zealand citizens/residents, the child will adopt the citizenship of the parents. In such cases, the parents of the newborn must report their birth status to their nationality at an embassy or consulate in New Zealand, apply for a national passport for the infant, and the infant may be legally resident with the parent's visa status at immigration in New Zealand
With a big belly to New Zealand "tourist son", newborns will not get New Zealand citizenship.