From 1985-1987, a total of 34 couples undergoing superovulation for a single in-vitro fertilization (IVF) cycle with clomiphene citrate and purified follicle stimulating hormone (FSH) or human menopausal gonadotrophin (HMG) were randomly allocated doses of intra-nasal buserelin to induce an endogenous gonadotrophin surge, prior to oocyte collection. The doses ranged from a single 25 µg dose to 100 µg every 4 h for 20 h. In three cycles the treatment was abandoned because of a poor ovarian

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... se. In the remaining 31 cycles buserelin was given to induce the endogenous gonadotrophin surge, but there was evidence of premature luteinization in eight cycles and a premature gonadotrophin surge in four cycles. Although a single dose as low as 40 µg induced a surge and resulted in a pregnancy, a single dose of 50 µg proved the most effective minimal dose consistently to induce a gonadotrophin surge and oocyte maturation. Recent reports using gonadotrophinreleasing hormone (GnRH) analogues to induce a gonadotrophin surge has prompted publication of this previously unpublished data.