Outcome from consecutive assisted reproduction cycles in patients treated with recombinant follitropin alfa filled-by-bioassay and those treated with recombinant follitropin alfa filled-by-mass.

Recent advances in manufacturing procedures for r-hFSH have resulted in a preparation (follitropin alfa) that is highly consistent in both isoform profile and glycan species distribution. As a result, follitropin alfa can be reliably quantified and vials can be filled by mass. This study compared the clinical results in a well-established assisted reproduction programme during the crossover from standard follitropin alfa filled-by-bioassay (FSH-bio) to follitropin alfa filled-by-mass (FSH-mass). The study included the last 125 patients treated with FSH-bio and the first 125 patients receiving FSH-mass for ovarian stimulation in their first assisted reproduction treatment cycle. Patient baseline characteristics were almost identical in the two groups. The duration of ovarian stimulation was significantly shorter in the FSH-mass group. The number of patients receiving the HCG injection and undergoing oocyte retrieval, follicular development and the serum concentration of oestradiol on the day of HCG injection were similar for the two treatment groups. The oocyte yield and the fertilization rates were similar in both groups of patients. However, embryo quality and implantation rates were significantly higher in the FSH-mass group. Accordingly, in spite of the mean number of embryos transferred being significantly lower in the FSH-mass group, there was a trend for higher clinical pregnancy rates in this group of patients. It is concluded that the new formulation of FSH-mass is more effective than the standard FSH-bio in terms of embryo quality, implantation rates, and number of days of stimulation.