Association between colonization with group B streptococci during pregnancy and preterm delivery among Danish women

Objective: We studied the relationship between group B streptococcal colonization and preterm delivery. Study Design: In this prospective study at a single hospital in Odense, Denmark, cervicovaginal cultures were obtained at ≤24 weeks’ gestation from all the women, at delivery from women with preterm deliveries, and from a random sample of women delivering at term. Results: In 2846 singleton births, there was no significant association between group B streptococcal colonization at ≤24 weeks’ gestation and preterm birth. After adjustment for the risk factors for preterm delivery, more women with preterm delivery (12/84, 14%) were colonized at delivery with group B streptococci than women with term deliveries (22/300, 7%; adjusted odds ratio, 3.0; 95% confidence interval, 1.4-6.8). Group B streptococcal colonization at ≤24 weeks’ gestation and at delivery was significantly less likely to occur in the presence of normal vaginal flora. Conclusion: Group B streptococcal colonization at delivery, but not at ≤24 weeks’ gestation, was associated with preterm delivery. (Am J Obstet Gynecol 2001;184:427-33.)