Originally: situated behind the uterus; retro-uterine (now rare). In later use: designating or representing the posterior branch of the uterus, or posterior genital tube, of a nematode.
2Designating, relating to, or occurring in the period of life after birth, as contrasted with the intrauterine period; post-natal.
Late 19th century; earliest use found in The Lancet. From post- + uterine.