Triggering final oocyte maturation with reduced doses of hCG in IVF/ICSI: a prospective, randomized and controlled study

Objective

To compare the effectiveness of urinary human chorionic gonadotropin (u-hCG) at reduced doses of 4000 IU and 6000 IU in inducing final oocyte maturation during in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycles.

Study design

164 patients with an indication for IVF or ICSI recruited in this randomized, single-blinded and controlled study in IVF clinic at the Sun Yat-sen Memorial Hospital. Patients were prospectively randomized to receive 4000 IU (Group A, n = 83) and 6000 IU (Group B, n = 81) of hCG for triggering final oocyte maturation. Number or percentage of mature oocytes retrieved per patient, fertilization rates, pregnancy rates were the main outcome measures.

Results

No evidence of statistically significant difference in the number or proportion of mature oocytes retrieved was observed in both groups. The lower fertilization rate and significantly lower clinical pregnancy rate were observed in Group A. The ovarian hyperstimulation syndrome (OHSS) rates in both groups were also similar. In the subgroup of BMI < 20 kg/m², fertilization rate were significantly higher in the administration group of hCG at the dose of 6000 IU when compared with the dose of 4000 IU (82.40% vs. 70.92%, P = 0.017); in contrast, no significant difference in clinical pregnancy rates was observed in both groups. In the subgroup of BMI 20-25 kg/m², clinical pregnancy rates were significantly higher in patients treated with hCG at dose of 6000 IU than patients treated with hCG at dose of 4000 IU (65.3% vs. 35.0%, P = 0.004); however, no significant difference in fertilization rates was observed.

Conclusion

Both doses of u-hCG revealed an equal effect on the induction of final oocyte maturation in the patients with moderate or high ovarian response; however, the reduced dose of hCG could result in an obvious impact on clinical pregnancy rates and did not exhibit an obvious effect on OHSS rates.