Does a newborn need a visa if entering her parents' country or just a passport?

I'm a South African 17-year-old and have an American green card because I lived in the U.S. I'm pregnant and going to give birth in NJ with my family.

Source: http://www.us-passport-service-guide.com/does-a-newborn-need-a-visa-if-entering-her-parents-country-or-just-a-passport.html

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