IVF or ISCI procedure and injection technique of embryo culture supernatant Controlled ovarian hyperstimulation was performed using a variety of protocols, as previously published elsewhere (8). A down-regulation of the pituitary was realized during triptorelin (Triptorelin Acetate Injection, Ferring, Germany) administration S.C., 0.1 mg/d×7, started from day 21 of the previous cycles. Ovarian stimulation started from day 3 of stimulated cycle by using recombinant follicle stimulating hormone (rFSH, Gonal-F, Serono, Switzerland), 225-300IU daily S.C.. The follicle development was monitored by transvaginal ultrasound scan (TVS). 250ug of HCG (Ovitrelle; Serono, Madrid) was administered by I.M. when one to two leading follicle(s) reached a mean diameter of 18 mm. In general, transvaginal oocyte retrieval was performed after 36 h of HCG injection.