Can 200 IU of hCG replace recombinant FSH in the late follicular phase in a GnRH-antagonist cycle? A pilot study

BACKGROUND: GnRH-antagonist protocols shorten the treatment period and reduce inconvenience for IVF patients. This randomised controlled trial (RCT) further explored whether low-dose hCG can be used clinically to replace recombinant FSH (rFSH) during the late follicular phase in a GnRH-antagonist protocol.

METHODS: Seventy ICSI patients undergoing controlled ovarian stimulation (COS) in a GnRH-antagonist protocol was randomized into two groups. The control group received a standard treatment with rFSH (Puregon) plus a GnRH-antagonist, daily from Day 6 of stimulation. In the study group, rFSH was discontinued when six follicles >or=12 mm were observed and estradiol levels were >600 ng/l; rFSH was subsequently replaced by low-dose hCG (200 IU/l daily).

RESULTS: Mean values (SD) for dose and duration of rFSH treatment in the control versus low-dose hCG group were 1617 (280) versus 1273 (260) IU rFSH [between-group difference -344, 95% confidence interval (CI) -483 to -205; P < 0.001], and 8.2 (1.6) versus 6.4 (1.3) days (-1.8, -2.6 to -1.1; P < 0.001), respectively. The mean number of metaphase II oocytes of 10.1 versus 8.9 (between-group difference -1.2, 95% CI -3.9 to 1.5) and the ongoing pregnancy rates of 10/35 (29%) versus 13/35 (37%) (between-group difference 8.6%; 95% CI -13.0 to 29.1%; P = 0.45) for control versus hCG, respectively, did not differ.

CONCLUSION: In this pilot trial, substitution of rFSH by low-dose hCG in the final days of COS leads to a reduction of FSH consumption whereas ICSI outcome, in terms of oocyte yield and ongoing pregnancy rate, remains comparable to the traditional regimen (ClinicalTrials.gov, trial number: NCT00750100).