A three step protocol for the treatment of idiopathic subfertility.

650 couples with idiopathic subfertility (mean duration: 5.7 year, range 2-21 years) were treated during 2870 cycles by three assisted conception methods (each involving mild ovarian stimulation): I timed intercourse (TI), II intrauterine insemination (IUI). III in vitro fertilization/embryo transfer (IVF/ET). Treatment started with TI in most cases and then changed to IUI after three to six cycles. Couples who failed to conceive were treated after another 3-9 cycles by IVF/ET. An overall cumulative pregnancy rate of 80.2% was reached after 18 treatment months. The pregnancy rates per treatment cycle were: TI 5.3%, IUI 6.9%, IVF/ET 15.8% (per oocyte retrieval).