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 less than or equal to 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 less than or equal to 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 8 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 less than or equal to 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 less than or equal to 24 weeks' gestation, was associated with preterm delivery.