Fig. 1

L. iners dominance is associated with a short cervix and preterm birth risk while L. crispatus is protective. a Heatmap of vaginal species data correlated community state types of samples (n = 161) with ethnicity, cervical length <25 mm, subsequent cerclage or progesterone intervention, and gestation at birth. b A short cervix <25 mm at 16 weeks was associated with a higher prevalence of L. iners (9/15, 60%) than longer cervical length (45/146, 31%, P = 0.04, two-tailed Fisher’s exact). c L. iners dominance was associated with early preterm birth <34⁺⁰ weeks (12/18, 67%), but not late preterm birth, 34⁺⁰ to 36⁺⁶ weeks (5/16, 31%) or term birth (37/127, 29%, P = 0.003). A greater proportion of term births had L. crispatus dominance at 16 weeks (63/127, 46%) than both late preterm (5/16, 31%) and early preterm births <34⁺⁰ weeks (2/18, 11%; P = 0.009; Fisher’s exact). d A Kaplan-Meier survival curve demonstrated that L. iners (n = 54) dominance at 16 weeks is associated with earlier gestation at delivery than a microbiome dominated by L. crispatus (n = 65, P = 0.02; Gehan-Breslow-Wilcoxon test)