Beneficial effects of a 24 h delay in human chorionic gonadotrophin administration during in-vitro fertilization...

We used a gonadotrophin-releasing hormone agonist (buserelin) and human menopausal gonadotrophin (HMG) for superovulation for in-vitro fertilization (IVF) in 143 patients. The patients were prospectively allocated to two balanced groups. In one group (47 patients) human chorionic gonadotrophin (HCG) was given when the three largest follicles were greater than or equal to 17 mm in diameter, with consistent levels of plasma oestradiol (standard group). In the second group (96 patients), HCG injection was delayed by 24 h (delayed group). In the delayed group of patients, proportionately more had clinical pregnancies (52.1% versus 34.0%). These results suggest that IVF patients will benefit from delayed administration of HCG. The traditional criteria for HCG administration should be changed when buserelin is used.