Ovulation

The goal of this clinical trial is to learn whether the sudden administration of vaginal micronized progesterone during the late follicular phase can trigger an LH surge and reactivation of oocyte meiosis in healthy oocyte donors aged 18 to 33 undergoing a mild ovarian stimulation cycle. The main question it aims to answer is: * Does progesterone administered in the late follicular phase induce an LH surge and subsequent oocyte meiosis reactivation? Participants will: * Undergo a mild ovarian stimulation with 75 IU of follitropn alfa * Start vaginal micronized progesterone (400 mg every 12 hours) once at least one follicle reaches 15 mm * Have blood samples collected to measure hormone levels before and after progesterone administration * Undergo oocyte retrieval 35-36 hours after the progesterone trigger This is a low-intervention, single-center pilot study including approximately 10 oocyte donors.

This study will compare different combinations of fertility signs (cervical mucus (CM), luteinizing hormone \[LH\], pregnanediol glucuronide \[PDG\], and basal body temperature \[BBT\]) to determine which are most reliable for identifying ovulation and luteal phase length. Thirty existing Premom App users will track daily observations for three menstrual cycles. Participants will record mucus, perform urine tests, upload test strip photos to the Premom App, and measure BBT. Both participant readings and AI-assisted app readings will be analyzed. The main goal is to find which marker pairings give the most accurate picture of ovulation timing and luteal phase length. Secondary goals include understanding ease of use, the number of tests required, and whether the app improves accuracy.

This is an observational longitudinal study to advance the understanding of menstrual cycle and gynecologic health conditions including PCOS, infertility and breast cancer.The study will be hosted within the Research app(available on App Store), which allows a user to find, enroll, and participate in Apple-supported health-related research studies.