Introduction Mindfulness-based stress reduction (MBSR) is a promising non-pharmacological approach to improve mental health during pregnancy. This study examined whether maternal MBSR is associated with changes in placental metabolic and endocrine function. Methods Placental samples were collected from participants in the IMPACT BCN randomized clinical trial, assigned to either MBSR or control care. Fatty acid composition was analysed by gas chromatography, gene expression by qPCR, and protein levels by Western blotting in placentas from male and female neonates. Results MBSR altered placental fatty acid composition, increasing several fatty acids (C20:2, C20:3n6, C22:0, C22:1n9) and reducing C24:0. Expression of ALOX15, a lipid signaling regulator, was reduced in the MBSR group, while genes involved in lipid metabolism, inflammation, and glucocorticoid pathways were largely unchanged. MBSR also decreased expression of key endocrine and steroidogenic genes (CSH1/2, CYP11A1, CYP19A1, HSD3B1), predominantly in male placentas. Consistently, STAT3 protein levels were reduced in males, indicating a potential change in endocrine signaling in response to MBSR. Discussion MBSR during pregnancy is associated with selective, sex-specific changes in placental lipid and endocrine pathways. These findings suggest that MBSR intervention influences placental function, potentially impacting fetal development.
