If one or both parents has been born and resides in Portugal, the child may automatically acquire Portuguese nationality. If not:
Acquire Portuguese citizenship:
Children born in Portuguese territory, the children of foreigners, if at the time of birth the mother or father has been legally resident for at least five years, and if none of them is in the service of their State, if they declare that they want to be Portuguese - Article 1, paragraph 1, point e) of the Nationality Law and Article 10 of the Nationality Regulation.
Children born in Portuguese territory, who prove that they do not have any nationality - Article 1, paragraph 1, point f) of the Nationality Law and Articles 3, c) and 6 of the Nationality Regulation.