Basing the investigators study on the evidence that basal serum androgens decrease with age, the investigators hypothesize that women with serum androgens below a certain level could be the population obtaining a benefit of Luteinizing Hormone (LH) supplementation. The objective of the present study is to explore the relationship between basal serum androgen levels and the need of LH for Controlled Ovarian Stimulation (COS) in IVF.