The Collaborative International Dictionary of English v.0.48:

Gravid \Grav"id\, a. [L. gravidus, fr. gravis heavy, loaded. See
   Grave, a.]
   Being with child; heavy with young; pregnant; fruitful; as, a
   gravid uterus; gravid piety; -- of animals as well as people.
   " His gravid associate." --Sir T. Herbert.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gravid
    adj 1: in an advanced stage of pregnancy; "was big with child";
           "was great with child" [syn: big(p), enceinte,
           expectant, gravid, great(p), large(p),
           heavy(p), with child(p)]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "gravid":
   anticipating, big, big with child, big-laden, breeding, carrying,
   carrying a fetus, expectant, expecting, gestating, gone, great,
   heavy, heavy with child, knocked up, parturient, preggers,
   pregnant, superfetate, superimpregnated, teeming, with child