Source : Webster's Revised Unabridged Dictionary (1913)

Postnatal \Post*na"tal\, a. [Pref. post- + natal.]
   After birth; subsequent to birth; as, postnatal infanticide;
   postnatal diseases.

Source : WordNet®

postnatal
     adj : occurring immediately after birth; "postnatal development"
           [syn: {postpartum}] [ant: {prenatal}, {perinatal}]