Oocyte Maturity in Relation to Woman's Age in In Vitro Fertilization Cycles Stimulated by Single Regimen

PURPOSE: During stimulated in vitro fertilization (IVF) cycle, up to 30% of the recovered oocytes are immature ones which have poor fertilization capacity; however, the precise influencing factors are largely unknown. Here, we analyzed the association of oocyte immaturity with woman's age in IVF cycles stimulated by single regimen. MATERIALS AND METHODS: A total of one-hundred ninety five IVF cycles stimulated by recombinant FSH and GnRH antagonist protocol between 2003 and 2009 were analyzed retrospectively. The mean age of women was 34.2±4.0 (26-45 years). After triggering by exogenous hCG, an ultrasound-guided retrieval of oocytes was performed 35-36 hours later. All clinical data were stratified by woman's age; group I: ≤30 (n=36), II: 31-35 (n=83), III: 36-40 (n=57), and IV: ≥41 (n=19). RESULTS: The total retrieved oocytes, as well as immature oocytes, were significantly lower in group IV, however, the mean % of immature oocytes was significantly higher in group IV than other age groups. Oocyte immaturity tended to decrease as increasing age in women aged 40 years or less. CONCLUSION: In stimulated IVF cycle, much higher oocyte immaturity was noted in women aged 41 years or more.