To Investigate the Cumulative Live Birth Rates Using GnRH Antagonist or Agonist Protocol for COS in ART Treatment

Recombinant FSH (Gonal-f®) will be administrated as routinely practiced by investigators. FSH doses will be adjusted according to the clinical experiences of investigators.The GnRH-ant (Cetrotide®) will be initiated in a fixed protocol on stimulation days 5 or 6 per the investigator's ART protocol.

The GnRH-a (Diphereline® or Decapetyl®) 0.1mg will be administered for about14 to 20 days for down-regulation. Gonal-f® will be administrated as routinely practiced by investigators. GnRH-a types, GnRH-a and FSH doses will be adjusted according to the clinical experiences of investigators in each site.