Immaturity and aneuploidy in human oocytes after different stimulation protocols

OBJECTIVE: To study immaturity and aneuploidy in human oocytes after two different stimulation protocols. DESIGN: Retrospective. SETTING: Outpatient IVF clinic/laboratory. PATIENTS: One hundred forty-three patients of whom 65 were stimulated with clomiphene citrate (CC)/human menopausal gonadotropin (hMG) and 78 were stimulated with gonadotropin-releasing hormone agonist (GnRH-a)/hMG. Only patients with at least one oocyte unfertilized were included in this study. RESULTS: Stimulation with GnRH-a/hMG, as compared with CC/hMG stimulation, resulted in larger numbers of oocytes (P less than 0.00001), a higher fertilization rate (P less than 0.02), and oocyte retrieval at a later average cycle day (P less than 0.000005). Cytogenetic findings of immaturity were observed in 33.9% of unfertilized oocytes after CC/hMG stimulation, compared with only 17.8% after GnRH-a/hMG stimulation (P less than 0.0005). Aneuploidy findings were the same for both groups. CONCLUSION: In GnRH-a/hMG stimulation, oocytes approach the normal day of ovulation more closely. This may allow for better oocyte maturation and higher fertilization and pregnancy rates.