Effects of Estrogen on Heart Health in Women With Primary Ovarian Insufficiency

Inclusion criteria (I): * female sex * age 30-40 * CASE PARTICIPANTS ONLY: clinically documented POI diagnosis within 6 months * CASE PARTICIPANTS ONLY: planning to clinically initiate 100mcg transdermal 17beta-estradiol twice weekly and micro-ionized progesterone (either 100mg daily or 200mg cyclically) * CONTROL PARTICIPANTS ONLY: regular menstrual cycles every 21-35 days Exclusion criteria (E): * CASE PARTICIPANTS ONLY: genetic POI etiology * CASE PARTICIPANTS ONLY: any prior initiation of ERT * systemic estrogen, progesterone or testosterone therapy within the past 6 months (including contraception, except for locally acting intrauterine devices - IUDs) * lipid lowering therapy within the past 6 months * use of antihypertensive medication within the past 6 months * current treatment with prescription, systemic (oral, IV, or IM) steroids or anti-inflammatory/immune suppressant medical therapies (excluding topical therapies, UV therapy, ASA-derivative therapies, or NSAIDS) for autoimmune/inflammatory diseases (psoriasis, RA, IBD, lupus), post-transplant care, asthma, or pain syndromes * use of oral steroids or prescription oral anti-inflammatory/immune suppressant medication for \>7 days within the past 1 month * use of IV or IM steroids or IV or IM anti-inflammatory/immune suppressant medication within the past 3 months * self-reported history of breast and/or estrogen dependent malignancy * self-reported history of deep vein thromboembolism, pulmonary embolism or strok…