How many eggs are needed to produce an assisted reproductive technology baby: Is more always better?

Objective: To evaluate the association between the number of mature (metaphase II [MII]) oocytes per assisted reproductive technology (ART) cycle and the likelihood of live birth. Design: Retrospective study. Setting: Academic infertility practice. Patient(s): Seven hundred thirty-seven infertile women undergoing their initial fresh embryo, nondonor IVF or intracytoplasmic sperm injection cycle at Montefiore's Institute for Reproductive Medicine and Health between January 2002 and December 2008. Intervention(s): None. Main Outcome Measure(s): Live birth. Result(s): Two hundred twenty-four cycles resulted in a live birth (30.4%). Live birth cycles had significantly more MII oocytes obtained per cycle as compared with their unsuccessful counterparts (11.0 ± 5.9 vs. 9.7 ± 6.2, respectively). Multivariate logistic regression was done to determine the minimum number of MII oocytes per cycle as a predictor of live birth after adjustment for age and historical maximum FSH values. Cycles that included the average number of MII in this cohort were used as a reference group. For cycles with five or fewer MII oocytes obtained, there was a statistically significant decrease in the likelihood of a live birth as compared with the reference group (odds ratio 0.61, 95% confidence interval 0.38-0.99). However, cycles with six or fewer obtained MII oocytes were not less likely to result in a live birth when compared with the reference group (odds ratio 0.69, 95% confidence interval 0.45-1.08). Conclusion(s): In our cohort, there was an advantage to obtaining six or more MII oocytes during the fresh oocyte retrieval compared with five or fewer oocytes. There was not an advantage, however, to obtaining 10 or more or 15 or more oocytes as compared with obtaining 6-9 oocytes. The strategy of aiming for a greater number of oocytes in an ART cycle should be revisited.