This observational study is initiated to collect information on the use of Cetrotide (GnRH antagonist) in ART cycles in routine practice across the Asia-Pacific region. The information will allow a better understanding of the current ovarian stimulation regimens that involve Cetrotide in the control of the endogenous gonadotrophin concentrations. The collection of live birth data, though a challenging task, as a secondary endpoint will allow the study to show valuable information on the final objective of ART. To minimize the potential variability due to the different ovarian stimulation agents, the study is to include cycles treated with Gonal-f (recombinant human FSH) since this agent is widely available in the region.