Corifollitropin alfa has been shown to result in significantly more oocytes compared to daily recombinant follicle stimulating hormone (recFSH) (Devroey et al., 2009), probably due to the higher circulating FSH activity during the first days of stimulation. For this reason, the use of corifollitropin alfa might be beneficial in poor responders in whom the number of oocytes retrieved is crucial for success.