Al-Memar M, Bobdiwala S, Fourie H, et al. - Researchers sought to describe vaginal bacterial composition in early pregnancy. Further, they examined how it is related to the first and second trimester miscarriages. They conducted a nested case-control study including 161 pregnancies in the setting of Queen Charlotte’s and Chelsea Hospital, Imperial College Healthcare NHS Trust, London; these comprised 64 pregnancies resulting in first-trimester miscarriage, 14 in second-trimester miscarriage and 83 term pregnancies. The analysis revealed association of first trimester miscarriage with reduced prevalence of Lactobacillus spp.-dominated vaginal microbiota classified using hierarchical clustering analysis (65.6 vs 87.7%), higher alpha diversity (mean Inverse Simpson Index 2.5 [95% confidence interval 1.8–3.0] vs 1.5 [1.3–1.7]) and higher richness 25.1 (18.5–31.7) vs 16.7 (13.4–20)), compared with viable pregnancies. This was noted independent of vaginal bleeding and was observable before first-trimester miscarriage diagnosis. Relative to missed miscarriage, incomplete/complete miscarriage was associated with higher proportions of Lactobacillus spp.-depleted communities. They observed similar early pregnancy vaginal bacterial stability between miscarriage and term pregnancies.