Impact of the Duration of Controlled Ovarian Stimulation on Assisted Reproduction Cycle Outcomes

Objective: To investigate the impact of duration of controlled ovarian stimulation on vitro fertilization outcomes.Study Design: Medical records of 3194 IVF and ICSI cycles from the assisted reproduction unit of a tertiary hospital were retrospectively analyzed using a computer based database. Characteristics of cycles with duration of stimulation ≤ 8 days (group I), 9 to 12 days (group II) or ≥13 days (group III) were studied retrospectively. Subgroup analysis was also done for poor responders, patients with polycystic ovary syndrome and normoresponders.Results: Estradiol on trigger day, number of retrieved oocytes, mature oocytes and fertilized oocytes were significantly higher in group II compared to the other two groups when all cycles were analyzed (p<0.001). No significant difference was observed regarding clinical and ongoing pregnancy rates between groups. Regarding poor responders, the number of mature oocytes and the number of fertilized oocytes were higher in group II compared to the other groups (p=0.028, p=0.038, respectively). Ongoing pregnancy rates were significantly lower in group III compared to other groups (p= 0.041). In patients with polycystic ovary syndrome, number of retrieved oocytes was significantly lower in group III compared to group II (p=0.047) and number of mature oocytes was significantly lower in group III compared to the other groups (p=0.005). No significant difference was found in the clinical and ongoing pregnancy rates. Number of retrieved oocytes, clinical and ongoing pregnancy rates were comparable between three groups for normoresponders.Conclusion: Prolonged cycles have a detrimental effect only on ongoing pregnancy rates in poor responders.