Importance of a 5-versus 7-day pill-free interval in a GnRH antagonist protocol using corifollitropin alfa: a prospective cohort study in oocyte donors

In this prospective cohort study, oocyte donors were recruited prospectively and assigned to receive corifollitropin alfa: 5 days after pill discontinuation (group D5; 42 donors), or 7 days after pill discontinuation (group D7; 50 donors) in a gonadotrophin-releasing hormone antagonist protocol. Fixed additional daily doses of 200 IU recombinent FSH (rFSH) were started after 7 days of corifollitropinalfa, until triggering. No significant differences in basal characteristics were observed between both groups. In group D5, mean (SD) total additional rFSH dose was 659 (452) IU; in group D7, total rFSH dose was 459 (356) IU (P = 0.022). Duration of stimulation was significantly longer in group D5 compared with group D7 (P = 0.002). No differences were found in total number of oocytes obtained. Total number of injections was significantly lower in group D7 compared with group D5 (9.8 [ 3.2] versus 11.9 [ 3.9], respectively; P = 0.004). Total cost of medication used for donor treatment was significantly higher in group D5 than in group D7 (P = 0.015). After more than 22 days of pill-taking, extending the pill-free interval to 7 days significantly reduces the total dose of gonadotrophins, duration of stimulation, total cost of medication and total number of injections. (C) 2017 Published by Elsevier Ltd on behalf of Reproductive Healthcare Ltd.