403. Independent Effects of Transdermal Estrogen and Oral Micronized Progesterone on Neuroactive Steroids Across the Menstrual Cycle: Descriptive Evidence From a Three-Period, Double-Blind, Crossover Randomized Controlled Trial in Patients With Suicidal Ideation

In reproductive-aged females, suicide risk increases perimenstrually, implicating estrogen (E2) and progesterone (P4) as time-varying suicidality triggers. Previously, our lab showed perimenstrual E2+P4 stabilization reduces suicidal ideation (SI) and increases P4-derived neuroactive steroids (NAS). We then separated E2 and P4, finding the benefit of E2+P4 on SI is driven by E2, but it is unknown how E2 alone affects NAS in menstruating individuals.