Late 16th century. From classical Latin praegnātus pregnant (2nd cent. a.d.), in post-classical Latin also used figuratively, use as adjective of past participle of praegnāre to make pregnant from praegnāt-, praegnās pregnant.

Late 17th century; earliest use found in Nahum Tate (c1652–1715), poet, playwright, and translator. From classical Latin praegnāt-, past participial stem of praegnāre to make pregnant.