BackgroundChildhood maltreatment (CM) exerts various long-lasting psychological and biological changes in affected individuals, with inflammation being an interconnecting element. Besides chronic low-grade inflammation, CM might also affect the energy production of cells by altering the function and density of mitochondria, i.e. the body's main energy suppliers. Here, we compared mitochondrial respiration and density in intact peripheral blood mononuclear cells (PBMC), from women with and without CM between two time points, i.e. at the highly inflammatory phase within 1 week after parturition (t0) and again after 1 year (t2).MethodsCM exposure was assessed with theChildhood Trauma Questionnaire. Whole blood was collected fromn= 52 healthy women within the study ‘My Childhood – Your Childhood’ at both time points to isolate and cryopreserve PBMC. Thawed PBMC were used to measure mitochondrial respiration and density by high-resolution respirometry followed by spectrophotometric analyses ofcitrate-synthaseactivity.ResultsOver time, quantitative respiratory parameters increased, while qualitative flux control ratios decreased, independently of CM. Women with CM showed higher mitochondrial respiration and density att0, but not att2. We found significant CM group × time interaction effects forATP-turnover-related respiration and mitochondrial density.ConclusionsThis is the first study to longitudinally investigate mitochondrial bioenergetics in postpartum women with and without CM. Our results indicate that CM-related mitochondrial alterations reflect allostatic load, probably due to higher inflammatory states during parturition, which normalize later. However, later inflammatory states might moderate the vulnerability for a second-hit on the level of mitochondrial bioenergetics, at least in immune cells.