Fonseca BM, Cunha SC, Gonçalves D, et al. - Researchers investigated the impacts of endocannabinoid anandamide (AEA) in uterine natural killer (uNK) cells from miscarriage decidua, concerning their cytokine profile and endometrial stromal cell (ESC) crosstalk. They here conducted a laboratory-based study using human primary uNK cells isolated from first-trimester decidua (gestational age, 5–12 weeks) derived from 8 women with elective pregnancy termination and 18 women who suffered a miscarriage. They performed an assessment of the first-trimester placental tissues for AEA levels using UPLC-MS/MS and for respective enzymatic profile using western blot. Compared with decidua from elective terminations, miscarriage decidua exhibited higher AEA levels. High TNF-α levels were identified in uNK-conditioned media from miscarriage samples which restrain ESC decidualization. Findings here suggest the modulating effect of endocannabinoid AEA in reproductive competence. Not only neuroendocrine homeostasis but also uterine changes occurring during early pregnancy seemed involving AEA.