The Collaborative International Dictionary of English v.0.48:

Obstetric \Ob*stet"ric\ ([o^]b*st[e^]t"r[i^]k), Obstetrical
\Ob*stet"ric*al\ ([o^]b*st[e^]t"r[i^]*kal), a. [L. obstetricius,
   fr. obstetrix, -icis, a midwife, fr. obstare to stand before:
   cf. F. obst['e]trique. See Obstacle.]
   1. Of or pertaining to childbirth, midwifery, or the period
      around the time of the birth of children; as, the
      obstetric art.
      [1913 Webster]

   2. Of or pertaining to obstetrics; as, the obstetric unit of
      a hospital.
      [PJC]

   Obstetrical toad (Zool.), a European toad of the genus
      Alytes, especially Alytes obstetricans. The eggs are
      laid in a string which the male winds around his legs, and
      carries about until the young are hatched.
      [1913 Webster]

WordNet (r) 3.0 (2006):

obstetrical
    adj 1: of or relating to or used in or practicing obstetrics;
           "obstetric hospital" [syn: obstetric, obstetrical]