The vaginal inflammatory milieu and the risk of early premature preterm rupture of membranes

Objective The purpose of this study was to determine the association of vaginal pH ≥5.0 and vaginal neutrophils >5 per oil field with preterm rupture of membranes (PPROM). Study design This was a secondary analysis of the Vaginal Infections and Prematurity cohort, and was comprised of 12,734 evaluable women enrolled between 23 and 26 weeksʹ gestation. Women were tested for sexually transmitted infections and vaginal pH. Gram-stained smears were used for the detection of neutrophils. Results In this analysis, 5751 (41.3%) women had neutrophils >5 per oil field, and 2500 (18.0%) had pH ≥5.0. Both elevated pH and neutrophils were present in 1149 women (8.3%). The concomitant presence of both neutrophils and elevated pH was significantly associated with PPROM at 24 to 32 weeks. Conclusion Elevated vaginal pH and neutrophils are most strongly associated with early third-trimester PPROM, reflecting the importance of infection and/or inflammation in the pathogenesis of this condition.