Low-dose FSH therapy for anovulatory infertility associated with polycystic ovary syndrome: rationale, results, reflections and refinements.

Low-dose follicle stimulating hormone (FSH) regimens for induction of ovulation for women with polycystic ovaries have succeeded in reducing the rate of ovarian hyperstimulation syndrome (OHSS) almost to nil and the rate of multiple pregnancies to a minimum of 6%. This has been achieved by reaching, but not exceeding, the threshold level of FSH, starting with a daily dose of 75 IU for 14 days, using small incremental dose rises where necessary, and inducing uniovulation in 70% of cycles. Conception rates are as good, if not better, than those achieved with conventional therapy. The miscarriage rate is still relatively high (20-25%) and obese women fare worse. Serum oestradiol concentrations and the number of large and intermediate follicles on the day of human chorionic gonadotrophin administration are much lower, in parallel with lower serum FSH concentrations. Inhibin values increase with the rise in serum FSH concentrations but those of luteinizing hormone decrease steadily throughout the follicular phase. New data using recombinant hFSH (rhFSH), rather than urinary gonadotrophin as the ovarian stimulant, demonstrate that treatment time is shortened. However, the ideal regimen has still to be formulated.