Colonization with group B streptococci in pregnancy and adverse outcome

OBJECTIVE: Our purpose was to study the association of cervicovaginal colonization with group B streptococci with pregnancy and neonatal outcome. STUDY DESIGN: A prospective study was conducted at seven medical centers between 1984 and 1989. Genital tract cultures were obtained at 23 to 26 weeksʹ gestation and at delivery. Prematurity and neonatal sepsis rates were compared between group B streptococci positive and negative women. RESULTS: Group B streptococci was recovered from 2877 (21%) of 13,646 women at enrollment. Heavy colonization was associated with a significant risk of delivering a preterm infant who had a low birth weight (odds ratio = 1.5, 95% confidence interval 1.1 to 1.9). Heavily colonized women given antibiotics effective against group B streptococci had little increased risk of a preterm, low-birth-weight birth. Women with light colonization were at the same risk of adverse outcome as the uncolonized women. Neonatal group B streptococci sepsis occurred in 2.6 of 1000 live births in women with and 1.6 of 1000 live births in women without group B streptococci at 23 to 26 weeksʹ gestation ( p = 0.11). However, sepsis occurred in 16 of 1000 live births to women with and 0.4 of 1000 live births to women without group B streptococci at delivery ( p< 0.001). CONCLUSIONS: Heavy group B streptococci colonization at 23 to 26 weeksʹ gestation was associated with an increased risk of delivering a preterm, low-birth-weight infant. Cervicovaginal colonization with group B streptococci at 23 to 26 weeksʹ gestation was not a reliable predictor of neonatal group B streptococci sepsis. Colonization at delivery was associated with sepsis. (AM J OBSTET GYNECOL 1996;174:1354-60.)