Change in Oocyte Yield in Repeated in Vitro Fertilization Cycles: Effect of Ovarian Reserve

Objective: To examine factors that affect variability in oocyte yield between consecutive IVF cycles.

Design: Retrospective cohort study.

Setting: University-based fertility clinic.

Patient(s): A total of 292 women starting two IVF cycles within 12 months from 2005 to 2011.

Intervention(s): Variables evaluated included female age, body mass index, parity, infertility diagnosis, antral follicle count (AFC), ovarian stimulation protocol, change in stimulation protocol, total dose of gonadotropin used and change in dose between cycles. Possible associations were tested using a log linear regression model.

Main Outcome Measure(s): Change in total and mature oocyte yield between cycles and factors that predict this change.

Result(s): In cycle 1, total and mature oocyte yield were positively associated with increased AFC and negatively associated with total gonadotropin dose. In cycle 2, a significant increase was seen in both total and mature oocytes. There were no significant independent variables that predicted this change in oocyte yield. When stratified into groups based on ovarian reserve, change in oocyte yield between cycles was significant only in patients with normal ovarian reserve (AFC >10). In this group, the only independent variable associated with an increased oocyte yield was an increase in the total gonadotropin dose.

Conclusion(s): An increase in oocyte yield between cycles was found in women with normal ovarian reserve and was associated with an increased total gonadotropin dose in the second cycle.