Simple aerobic bacterial culture of the vaginal swab at the time of cerclage could serve as a reliable test to predict subsequent preterm delivery, suggests a new study published in the Journal of Maternal-Fetal and Neonatal Medicine. The retrospective case-control study sought to determine predictors of preterm delivery after rescue cerclage. Data was aggregated from all pregnant women who underwent rescue cerclage before 26+0 gestational weeks between July 2006 and July 2016. These women were divided into delivery at <34 weeks group (n = 12) and delivery at ≥34 weeks group (n = 12). Gestational weeks at cerclage ≥23 and positive vaginal culture at cerclage appeared to be significantly more prevalent in the ‘delivery at <34 weeks’ group than in the ‘delivery at ≥34 weeks’ group. Prolapsed membranes at cerclage appeared to be more prevalent in the ‘delivery at <34 weeks’ group as compared to the ‘delivery at ≥34 weeks’ group. ‘Positive vaginal culture at cerclage was the only independent risk factor associated with subsequent preterm delivery before 34 gestational weeks. The researchers thus concluded that a simple aerobic bacterial culture at the time of cerclage seems to be a valuable test to predict subsequent preterm delivery before 34 gestational weeks.