MILD ovarian stimulation with GnRH-antagonist vs. long protocol with low dose FSH for non-PCO high responders undergoing IVF: a prospective, randomized study including thawing cycles.

OBJECTIVE: To compare the effectiveness of two stimulation protocols in non-polycystic ovary (PCO) high responders undergoing in vitro fertilization (IVF). DESIGN: Prospective randomized trial. SETTING: A Reproductive Medicine and IVF Unit of a University Hospital and a private IVF Clinic. METHODS: Four hundred-and-twelve normoovulatory women with good ovarian responsiveness were randomized to receive either the "mild" (FSH 150 IU/day from day 4 of a spontaneous cycle followed by GnRH-antagonist from day 8; n = 205) or the "long" (FSH 150 IU/day; n = 207) stimulation protocol. The outcome of these two regimens was compared including "fresh" and thawing cycles. RESULTS: The total FSH dose and the peak estradiol level were significantly lower in the "mild" protocol, whereas the retrieved oocytes, fertilization rate, number and quality of embryos, pregnancy and implantation rates, cumulative "fresh plus thaw" success rate, and incidence of severe ovarian hyperstimulation syndrome were comparable with the two regimens. CONCLUSIONS: In young, normoovulatory patients with good ovarian responsiveness undergoing IVF the "mild" stimulation protocol has effectiveness and risks comparable to the "long" protocol with low FSH starting dose, even when thawing cycles are included in the comparison.