Group B Streptococcus (GBS) Colonization and Disease among Pregnant Women: A Historical Cohort Study
Table 3
Incidence and relative risk of adverse pregnancy outcomes by GBS colonization status.
GBS Negative
GBS Colonized
Invasive GBS
(N=47,013),
(N=12,952),
(N=64),
Outcome
n ()
n ()
n ()
RR (95% CI)
aRR1 (95% CI)
Gestational diabetes
1515 (3.2%)
559 (4.3%)
12 (18.8%)+
1.34 (1.22, 1.47)
1.21 (1.11, 1.32)
Gestational hypertension/preeclampsia
5397 (11.5)
1585 (12.2%)
9 (14.1%)
1.07 (1.01, 1.12)
0.98 (0.93, 1.04)
Pyelonephritis
412 (0.9%)
140 (1.1%)
1 (1.6%)
1.23 (1.02, 1.49)
1.12 (0.90, 1.38)
Short cervix
760 (1.6%)
172 (1.3%)
7 (10.9%)+
0.82 (0.70, 0.97)
0.64 (0.52, 0.79)
Preterm labor
5528 (11.8%)
1532 (11.8%)
15 (23.4%)+
1.01 (0.95, 1.06)
0.96 (0.90, 1.02)
Preterm Birth, < 34 weeks
2812 (6.2%)
273 (2.2%)
11 (17.7%)+
0.35 (0.31, 0.40)
0.30 (0.26, 0.35)
Preterm Birth, < 37 weeks
6550 (14.4%)
1003 (8.0%)
20 (32.3%)
0.55 (0.52, 0.59)
0.49 (0.45, 0.53)
Chorioamnionitis
1654 (3.5%)
386 (3.0%)
10 (15.6%)+
0.85 (0.76, 0.94)
0.76 (0.66, 0.87)
Operative delivery
17354 (36.9%)
4088 (31.6%)
27 (42.2%)
0.85 (0.83, 0.88)
0.85 (0.83, 0.88)
Wound infection
1161 (2.5%)
257 (2.0%)
9 (14.1%)+
0.80 (0.70, 0.92)
0.75 (0.64, 0.88)
Endometritis
142 (0.3%)
50 (0.4%)
3 (4.7%)+
1.28 (0.93, 1.76)
1.03 (0.72, 1.49)
Sepsis
41 (0.1%)
15 (0.1%)
2 (3.1%)+
1.33 (0.74, 2.40)
1.45 (0.74, 2.85)
Mastitis
82 (0.2%)
31 (0.2%)
0
1.37 (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.
