firstborn

It meant something socially and legally to be the first-born son, a son at all, or a girl.

Content, my mother was at ease that her first-born would not fall into the ranks of picky eaters.

It is to the first-born, whether a boy or a girl, that the inheritance is transmitted, and he or she is forbidden to abandon it.

The first one hit, of the happy couple, betokens the sex of their first-born.