Different ovarian stimulation regimens have shown to modify late follicular phase hormonal profiles. Besides, recent studies confirm that progesterone levels and their variation in the last day of oocyte maturation are affected by the dose of gonadotropins administered and by other factors. Progesterone elevation in late follicular phase of in vitro fertilization/intracytoplasmatic sperm injection (IVF/ICSI) cycles under ovarian stimulation compromises implantation rates due to a negative effect on the endometrium. However, there is still conflict in the literature questioning whether progesterone levels alone on the triggering day is a sufficient indicator as progesterone does not give the full picture of the ovarian functions, number of follicles as well as estrogen production that facilitate endometrial growth, thus some studies suggest that especially in aged and poor responders Progesterone/Estrogen (P4/E2) ratio has a better reflection (Progesterone (ng/mL) ×1,000/estradiol(pg/mL)) on the ovarian function. The scope of the current pilot study is to compare serum progesterone levels as well as P4/E2 ratio on the day of ovulation triggering of women belonging to POSEIDON category group 2 who undergo a new ovarian stimulation with a dose of rhFSH 300 IU or 300 IU rhFSH plus 150 IU recombinant human luteinizing hormone (rhLH) in a gonadotropin-releasing hormone (GnRH) antagonist protocol.