The aim of this study is to assess the oocyte yield of infertile women with suspected or known poor ovarian reserve (POR) undergoing a GnRH antagonist protocol for IVF with Merional® starting either with a low (150 IU) or a high dose (450 IU) and adding 100mg of CC (Serophene®) in the early follicular phase of the stimulation (day 3 to 7). To date no RCT has been conducted to compare the reproductive outcome of patients with POR as defined by the ESHRE Bologna criteria after controlled ovarian hyperstimulation with HMG in an GnRH antagonist protocol using low doses versus high doses of HMG and adding CC versus placebo. We hypothesize that adding 100 mg of CC on day 3-7 to a HMG antagonist protocol will lead to an additional increment of endogenous GT thus increasing the oocytes yield after controlled ovarian stimulation due to higher endogenous gonadotropin secretion.