Vaginal douching, bacterial vaginosis, and spontaneous preterm birth.

Abstract Objective Vaginal douching and bacterial vaginosis (BV) are independently associated with spontaneous preterm birth. Because the interrelationships among these variables remain unclear, we sought to examine the associations in a prospective study. Methods We conducted a nested case-control study within a prospectively recruited cohort of pregnant women. We prospectively collected demographic and health status data, data on pre-pregnancy vaginal douching, vaginal smears for bacterial vaginosis as defined by Nugent's criteria, fetal fibronectin at 26 weeks of pregnancy, and placental pathology at delivery. Spontaneous preterm births before 37 weeks' gestation were selected as cases. All spontaneous births occurring after 37 weeks were potential control subjects. To limit costs, some tests were performed only in selected control subjects. Results Preterm birth occurred in 207 of 5092 women (4.1%). In bivariate analysis, BV was not associated with preterm birth (OR 1.2; 95% CI 0.5 to 2.4). Vaginal douching was significantly associated with bacterial vaginosis ( P P Conclusion Vaginal douching and bacterial vaginosis were not associated with spontaneous preterm birth overall. However, vaginal douching appears to be an independent and potentially modifiable risk factor for early preterm birth (32-34 weeks), although the mechanism remains unclear.