Clomiphene Citrate as An Adjuvant to hMG Stimulation of the Ovaries in Mid-to-late Follicular Phase and Subsequently Pregnancy Outcome of Frozen-thawed Embryo Transfers

Objective To compare the results of a novel regimen of human menopausal gonadotrophin （hMG） in combination with clomiphene citrate （CC） in mid-to-late follicular phase with those of a short protocol of GnRH agonist （GnRHa） and hMG used for IVF. Methods In the retrospective study, 842 patients undergoing IVF were collected and classified into two groups： hMG in combination with CC in mid-to-late follicular phase （group A, n=319） and short protocol of GnRHa-hMG （group B, n=523）. The main outcome measures were ovarian responses in stimulation cycles and pregnancy outcomes in subsequent frozen-thawed embryo transfer （FET） cycles. Results In group A, the serum LH concentration on day 8 -10 was similar with that on the day of hCG administration （2.43 ± 1.92 IU vs 2.51 ±2.05 IU）. The number of mature follicles and oocytes retrieved was significantly lower in group A than in group B while the fertilization rate and the cleavage rate were comparable. The clinical pregnancy rate （47. 79% vs 48.04%）, the implantation rate （32.49% vs 33.11%） and the cumulative pregnancy rate （58.09% vs 60.22%） were respectively similar in group A and group B. Conclusion hMG in combination with CC in mid-to-late follicular phase results in the same pregnancy outcome as short protocol. The novel protocol may take the advantage of eliminating the occurrehce of a premature endogenous LH Surge.