Background: Pregnant veterans are a subpopulation known to be at elevated risk of developing mental health symptoms, such as depression and suicidal ideation. Inflammation has been associated with depression, specifically during the perinatal period. Critical changes in estradiol, cortisol, and inflammatory cytokines are necessary for the progression of a healthy pregnancy, which are then rapidly altered in the postpartum period. We explored changes in estradiol, cortisol, and pro-inflammatory cytokines relative to depressive symptoms and suicidal thoughts across pregnancy and postpartum in this pilot and feasibility study. Methods: We measured estradiol, cortisol, and the inflammatory cytokines IL-1β, IL-6, IL-8, IFN-γ, and TNF-α in 18 pregnant veterans and analyzed the data using descriptive statistics, dependent t-tests, and correlation analyses. We assessed depression severity with the Edinburgh Postnatal Depression Scale and suicidality with the Columbia-Suicide Severity Rating Scale. Thirteen of the women repeated assessments in the early postpartum period at an average of 6.7 weeks after birth. Results: As anticipated, estradiol (t(12) = 12.47, p