Yo utilizaría "legitimate" en este contexto..

At common law, legitimacy is the status of a child who is born to parents who are legally married to one another, or who is born shortly after the parents' marriage ends through divorce. In both canon and civil law, the offspring of putative marriages have been considered legitimate. For the opposite of legitimacy, the term illegitimate has been used about a child born to a woman and a man not married to one another, though in many societies today such terminology has become obsolete even in law, and abandoned in common communication in favor of less abrasive words such as extramarital or love child.