Table 3: Incidence and relative risk of adverse pregnancy outcomes by GBS colonization status.

GBS NegativeGBS ColonizedInvasive GBS
(N=47,013),(N=12,952),(N=64),
Outcomen ()n ()n ()RR (95% CI)aRR1 (95% CI)

Gestational diabetes1515 (3.2%)559 (4.3%)12 (18.8%)+1.34 (1.22, 1.47)1.21 (1.11, 1.32)
Gestational hypertension/preeclampsia5397 (11.5)1585 (12.2%)9 (14.1%)1.07 (1.01, 1.12)0.98 (0.93, 1.04)
Pyelonephritis412 (0.9%)140 (1.1%)1 (1.6%)1.23 (1.02, 1.49)1.12 (0.90, 1.38)
Short cervix760 (1.6%)172 (1.3%)7 (10.9%)+0.82 (0.70, 0.97)0.64 (0.52, 0.79)
Preterm labor5528 (11.8%)1532 (11.8%)15 (23.4%)+1.01 (0.95, 1.06)0.96 (0.90, 1.02)
Preterm Birth, < 34 weeks2812 (6.2%)273 (2.2%)11 (17.7%)+0.35 (0.31, 0.40)0.30 (0.26, 0.35)
Preterm Birth, < 37 weeks6550 (14.4%)1003 (8.0%)20 (32.3%)0.55 (0.52, 0.59)0.49 (0.45, 0.53)
Chorioamnionitis1654 (3.5%)386 (3.0%)10 (15.6%)+0.85 (0.76, 0.94)0.76 (0.66, 0.87)
Operative delivery17354 (36.9%)4088 (31.6%)27 (42.2%)0.85 (0.83, 0.88)0.85 (0.83, 0.88)
Wound infection1161 (2.5%)257 (2.0%)9 (14.1%)+0.80 (0.70, 0.92)0.75 (0.64, 0.88)
Endometritis142 (0.3%)50 (0.4%)3 (4.7%)+1.28 (0.93, 1.76)1.03 (0.72, 1.49)
Sepsis41 (0.1%)15 (0.1%)2 (3.1%)+1.33 (0.74, 2.40)1.45 (0.74, 2.85)
Mastitis82 (0.2%)31 (0.2%)01.37 (0.91, 2.07)1.12 (0.69, 1.82)

% = n/column N.
RR = relative risk, aRR = adjusted relative risk, and CI = confidence interval.
RR and aRR reported for GBS colonized versus GBS negative.
1Adjusted for age, race, chronic hypertension, preexisting diabetes, and tobacco use.
+Fisher’s exact p <0.05 for comparison of invasive GBS versus GBS colonized.