Comparing the Pharmacokinetics of a Progesterone Ring Versus a Progesterone Vaginal Insert

Inclusion Criteria: * Individuals assigned female at birth who are post-menopausal, women 40 to 65 years of age, inclusive. Postmenopausal is defined as 6-months of spontaneous amenorrhea with serum FSH levels \> 40 mIU/mL (if not taking systemic hormone therapy) or 6 weeks postsurgical bilateral oophorectomy with or without hysterectomy. * Able and willing to correctly and independently complete all study procedures. * Able to read, understand, and provide written informed consent after the nature of the study has been fully explained and must be willing to comply with all study requirements and procedures. * VA vaginal pH of ≤ 5.0. Women with vaginal atrophy may rescreen at least 6 weeks after starting either systemic or topical estradiol therapy. * Women who are taking systemic (e.g. oral, injectable, transdermal) progesterone (P4) therapy must have at least 2 weeks of wash out from the last dose prior to visit 2. Exclusion Criteria: * Subjects with clinically significant chronic kidney disease defined as Glomerular Filtration Rate of \<60 mL/min/1.73m2 * Subjects with uninvestigated hematuria * Subjects with known nephrolithiasis, known polycystic kidney disease (PKD), or other known renal genetic disorders * Subjects with prior pelvic malignancies requiring radiation therapy, or whose surgery for such has led to complications such as fistulas, etc. * Subjects with a history of any severe acute or chronic medical or psychiatric condition or laboratory abnormality that …