WordNet (r) 3.0 (2006):

blessed event
    n 1: the live birth of a child [syn: blessed event, happy
         event]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "blessed event":
   accouchement, birth, birth throes, birthing, childbearing,
   childbed, childbirth, confinement, delivery, genesis, giving birth,
   hatching, having a baby, labor, multiparity, nascency, nativity,
   parturition, the Nativity, the stork, travail