New Zealand is also one of the countries that allows dual citizenship, although we have some countries that do not give room for such opportunity. Dual citizenship allows a man to be a citizen of two countries at the same time. There are many conditions that must be met before you can get New Zealand citizenship. One important part of the conditions is that the country you are coming from must also allow dual citizenship, if not you won't be given New Zealand citizenship unless you can stop being a citizen of that country and get New Zealand citizenship.
And also if you give birth in New Zealand and you or the other parent is from New Zealand, the baby will automatically be registered as a New Zealand citizen. More so, you might need to give up on New Zealand citizenship if you are applying to be a citizen of a country that does allow dual citizenship