Ovulation

Currently, the gold standard to confirm ovulation is measuring LH and/or progesterone in blood. However, because confirmation requires a blood sample, this approach is not suitable for epidemiological studies evaluating the impact of various factors on ovulation. Additionally, in cases of irregular menstrual cycles, there is additional difficulty in determining when the blood sample should be taken. Our objective is the development of non-invasive markers of ovulation (salivary and hair progesterone) in women with regular menstrual cycles over a period of 3 menstrual cycles. Our hypothesis is that there is a correlation between ovulation detection, using the "gold standard" i.e. detection of the pre-ovulatory LH surge associated with an increase in progesterone during the mid-luteal phase, and the mean level of hair progesterone measured between 2 menstrual cycles. Various studies have shown that, to be functional, the female reproductive axis requires an intact circadian system characterized by the existence of biological clocks called "clock genes" which are expressed in 24-hour cycles. In rodent, mutations in these "clock genes" lead to irregular menstrual cycles and alterations in the preovulatory LH surge. A quantitative measurement (using quantitative RT-PCR) of clock gene expression in the oral cavity will be performed. Since the reproductive system is also under the influence of locomotor activity and diet, all of these parameters will also be analyzed using participants' smartphones and connected smartwatches.

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 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.