['Previous reports have suggested that the ovarian response to leuprolide acetate is predictive of in vitro fertilization pregnancy rates. This study evaluated the outcome of in vitro fertilization cycles complicated by elevated estradiol levels during leuprolide acetate down regulation and the outcome of subsequent cycles in the same patients.', 'Two hundred fifty-two in vitro fertilization cycles were initiated utilizing leuprolide acetate down regulation beginning on cycle day 1.', 'Seventy-four of these cycles had an elevated estradiol level at the time of the baseline scan (28%). This group of patients had a higher maternal age, a higher cycle cancellation rate (27.5 vs 16.3%), and a high rate of recurrence on subsequent cycles (63%).'] Is ovarian activity during follicular-phase down regulation in in vitro fertilization associated with advanced maternal age and a high recurrence rate in subsequent cycles?