Subcutaneous Progesterone Versus Vaginal Progesterone Gel for Luteal Phase Support in Patients Undergoing In-Vitro Fertilization (IVF)

Inclusion Criteria: * Age 18- 42 (upon starting COH); * BMI \<30 kg/m2; * \<3 prior ART cycles (IVF, ICSI and related procedures); * Baseline (day 2-3 of cycling) FSH \<15 IU/L and E2 \<80 pg/mL; * Normal uterine cavity as per recent hysterosalpingogram, sonohysterogram or hysteroscopic exam (i.e. no polyp or protruding sub-mucosal fibroid); * At least 3 retrieved oocytes; * Patient has given written informed consent. Exclusion Criteria: * Intramural uterine fibroids that distort the uterine cavity or polyps \>1 cm; * Stage III or IV endometriosis (endometriomas); * Hydrosalpinx; * History of past poor response to COH resulting in canceling ART; * Use of thawed/donated oocytes; * Use of thawed/donated embryos; * Patients affected by pathologies associated with any contraindication of being pregnant; * Hypersensitivity to study medication; * Uncontrolled adrenal or thyroid dysfunction; * Undiagnosed vaginal bleeding; * History of arterial disease; * Patients with hepatic impairment; * Neoplasias (current) or history of neoplasia that may be responsive to progesterone; * High grade cervical dysplasia; * Active thrombophlebitis or thromboembolic disorders, or a history of hormone-associated thrombophlebitis or thromboembolic disorders; * History of recurrent pregnancy loss defined as 3 or more spontaneous miscarriages wherein pregnancy developed to a minimum of a gestational sac on TVUS; * Participation in a concurrent clinical trial or another trial within the past 2 months; * Use of concomitant medications that might interfere with the study evaluation; * Pre-implantation genetic diagnosis/screening.