Cumulative pregnancy rates after three cycles of minimal stimulation IVF and results according to subfertility diagnosis: a multicentre cohort study.

BACKGROUND: In minimal stimulation IVF, treatment is aimed at using the single oocyte that spontaneously develops to dominance. To prevent untimely ovulation, a GnRH antagonist is administered in the late follicular phase of the natural cycle together with recombinant FSH for substitution. Owing to the lack of ovarian stimulation, minimal stimulation IVF is a low-risk and patient-friendly treatment. In this study, effectiveness of minimal stimulation IVF was studied. METHODS: In this prospective multicentre cohort study, minimal stimulation IVF was offered to 350 patients. All indications for conventional IVF were included. Main outcome measures were pregnancy rates per cycle and cumulative pregnancy rates after three cycles. RESULTS: A total of 336 patients completed 844 cycles (2.5 per patient). The overall ongoing pregnancy rate per started cycle was 8.3% [95% confidence interval (CI) 6.4-10.2%]. The cumulative ongoing pregnancy rate after up to three cycles was 20.8% (95% CI 16.4-25.3%) per patient. No differences were found according to indication for IVF. CONCLUSIONS: Minimal stimulation IVF seems suitable for all indications studied. Pregnancy rates are encouraging. Owing to the low-risk and patient-friendly nature of this protocol, it seems a feasible treatment option for patients requiring IVF.