1. Perimenopause Status: We will employ the Stages of Reproductive Aging Workshop (STRAW) criteria70 to confirm perimenopausal status. The stages are primarily based on the characteristics of the menstrual cycle and secondarily on follicle stimulating hormone (FSH) levels. The anchor for the staging system is the final menstrual period (FMP). We will enroll women who have ≥ 2 skipped cycles and an interval of amenorrhea ≥ 60 days, consistent with the late menopause transition (stage -1), and who demonstrate an FSH level > 25 IU/mL. Because extremes of body weight (BMI < 18 or > 30 kg/m2) or a history of chronic menstrual cycle irregularity can contribute to inaccurate reproductive staging, these will serve as additional exclusion criteria;