Maternal Peripartum Complications Associated with Vaginal Group B Streptococci Colonization

The study was done to determine the risk of clinically diagnosed intra-amniotic infection (IAI) and postpartum endometritis (PPE) associated with vaginal group B streptococci (GBS) colonization. Pregnant women were enrolled in a cross-sectional, observational study from 1992 to 1996 in Houston (n = 908), Seattle (n = 2676), and Pittsburgh (n = 4338). Swab samples were obtained from the lower vagina of participants at admission for delivery and inoculated into selective broth and onto blood agar media. At the combined centers, 2.9% of the women (231/7922) had IAI, and 2.0% (157/7922) had PPE. The risk of IAI was higher for women with heavy GBS colonization (odds ratio [OR], 2.0; 95% confidence interval [95% CI], 1.1–3.7) than for those with light colonization (OR, 1.2; 95% CI, 0.7–1.8). The risk of GBS-associated PPE was not influenced by density of colonization (OR, 1.8; 95% CI, 1.3–2.7). These findings provide further evidence that GBS is associated with maternal intrapartum complications.