A group of 130 women undergoing conventional COS after pituitary down-regulation for IVF will be studied to determine the best cut-off points of AMH, using receiver operating characteristic (ROC) analysis, to discriminate excessive (≥20 oocytes retrieved) and poor response (≤4 oocytes retrieved). The inclusion criteria is any patient with indication of IVF treatment. Subsequently, a different group of 120 women (with the same criteria) will be assessed using AMH before starting COS, and treatment strategy will be individualized according to AMH results (iCOS). Mild stimulation using daily doses (112.5 to 150 IU) of recombinant follicle stimulation hormone (rec-hFSH) or rec-hFSH combined with recombinant luteinizing hormone (LH) supplementation (375 IU total daily dose) will be given to patients identified as at risk of excessive and poor response, respectively. It will evaluated: number of oocytes, clinical pregnancy rates (defined as fetal heartbeat on ultrasound performed 4 weeks after the transfer of embryos) and occurrence of Ovarian hyperstimulation syndrome). Outcomes will be compared between the groups who received conventional and iCOS using chi-square and Fisher exact tests.