Distinct vaginal microbial signatures in pregnancies complicated by antiphospholipid syndrome: depletion of

Antiphospholipid syndrome (APS) is a systemic autoimmune disease that contributes substantially to recurrent pregnancy loss, fetal death, intrauterine growth restriction, and preeclampsia, posing major threats to maternal and fetal health. These obstetric complications exhibit clinical similarities to those resulting from vaginal dysbiosis, yet the vaginal microbiota in APS pregnancies has not been systematically investigated. In this study, we characterized the vaginal microbiome in 33 pregnant women with APS and 90 healthy controls using 16S rRNA gene sequencing. We identified a unique microbial signature in APS pregnancies that differed from the commonly observed pattern of increased microbial diversity and IMPORTANCE: Antiphospholipid syndrome (APS) is an autoimmune disease that causes recurrent miscarriage, fetal death, and pregnancy complications in women of reproductive age. While coagulation dysfunction is a known contributing factor, whether APS is accompanied by vaginal microbiota alterations and their role in adverse outcomes remains unclear. We discovered that pregnant women with antiphospholipid syndrome harbor a unique vaginal microbial community: they exhibit depletion of the protective species