['to evaluate whether the duration of gonadotropin stimulation predicts the likelihood of live birth after ART.', 'all IVF or ICSI cycles using fresh autologous oocytes at our institution between January 2004 and December 2007 were analyzed.', 'out of 699 cycles resulting in oocyte retrieval, 193 produced a live birth (27.6%). Women who achieved a live birth had a significantly shorter stimulation phase (11.1 vs. 11.5 days, respectively). Multivariable analysis suggested that 13 days or longer of stimulation decreased the likelihood of a live birth by 53% as compared to cycles that were 10-12 days long (odds ratio [OR] 0.47; 95% confidence interval [CI]: 0.30-0.75) after adjustment for female age, maximum historical FSH, total dose of gonadotropin received, oocytes retrieved, embryos transferred, antagonist suppression and PCOS diagnosis.'] Is prolonged gonadotropin stimulation associated with decreased ART success?