Rekovelle

Women underwent routine ovarian stimulation by either a GnRH-agonist or -antagonist co-treatment protocol with recombinant- or urinary- follicle stimulating hormone (FSH; Bemfola, Gedeon Richter, Belgium, Menopur, Ferring, St. Prex, Switzerland, Gonal-F, Merck Serono, Switzerland or Rekovelle, Ferring, St. Prex, Switzerland) [42 (link)]. Ovarian stimulation protocols are standardized at our center and the distribution of GnRH-agonist or antagonist protocol reflects policy changes over time and not patient selection. Human recombinant chorionic gonadotropin (hCG) (Pregnyl, Organon, the Netherlands) was used as a trigger of final follicular maturation. Ovum pick up was planned according to standardized criteria. For ICSI with ejaculated sperm, metaphase II (MII) oocytes were injected with motile ejaculated spermatozoa. For ICSI with testicular sperm, MII oocytes were injected with either motile testicular spermatozoa or immotile but viable testicular spermatozoa, as selected by a sperm tail flexibility test [43 (link)].

Women were randomised in a 1:1 ratio to treatment with either follitropin delta (Rekovelle; Ferring Pharmaceuticals, Saint-Prex, Switzerland) or follitropin alfa (Gonal-f; Merck Serono, Geneva, Switzerland) via a central computer-generated randomisation list, prepared by an independent statistician. The randomisation was stratified by centre and age (<35, 35–37 and 38–40 years) using a block size of four. All investigators, embryologists and central laboratory personnel were blinded to the individual treatment allocation.