Female reproductive tract microbiota and recurrent pregnancy loss: a nested case-control study

•Recurrent pregnancy loss often remains unexplained in standard examinations•16S rRNA gene amplicon sequencing is used to analyse the reproductive tract microbiota•The endometrium has its own microbiota, with a composition close to that of the vaginal microbiota•A dysbiotic reproductive tract microbiota is associated with recurrent miscarriages•A dysbiotic endometrial microbiota may be a novel background cause for miscarriages