Table A1.

Allocation of Risk for Neonatal Group B Streptococcal Sepsis—Effects of Gestational Age, Intrapartum Factors, and Maternal GBS Colonization

Risk FactorsPrevalence
(%)
Attack
Rate
GBS Cases in Category
Maternal Screening for
GBS Colonization
EGA
(Weeks)
Fever or
PROM
Per 1000
Total Births
% of Total
GBS Cases
None<28Absent0.740.02780.2056.84
<28Present0.060.25350.1535.11
28–30Absent0.830.01230.1033.42
28–30Present0.070.12940.0882.93
31–33Absent1.940.00560.1093.63
31–33Present0.160.06300.1003.33
34–36Absent6.010.00260.1585.26
34–36Present0.490.03040.1494.97
≥37Absent82.920.00120.98732.91
≥37Present6.780.01400.94831.59
Rectovaginal culture at 35–37 weeks: Not done<37Absent9.520.00600.57519.16
<37Present0.780.06300.49016.34
Rectovaginal culture at 35–37 weeks: No GBS≥37Absent64.040.00020.0973.22
≥37Present5.230.00180.0973.23
Rectovaginal culture at 35–37 weeks: GBS +≥37Absent18.880.00470.89129.69
≥37Present1.540.05510.85128.36
Vaginal culture in labor: No GBS<28Absent0.630.00020.0010.05
<28Present0.050.12590.0652.17
28–30Absent0.710.000090.0010.02
28–30Present0.060.00530.0030.10
31–33Absent1.660.000040.0010.02
31–33Present0.140.00070.0010.03
34–36Absent5.130.000020.0010.03
34–36Present0.420.00020.0010.03
≥37Absent70.740.000010.0050.18
≥37Present5.780.00010.0050.19
Vaginal culture in labor: GBS +<28Absent0.110.18770.2046.79
<28Present0.010.99350.0882.94
28–30Absent0.120.08350.1023.40
28–30Present0.010.85040.0852.83
31–33Absent0.290.03800.1093.61
31–33Present0.020.42480.0943.30
34–36Absent0.880.01780.1575.23
34–36Present0.070.20530.1484.94
≥37Absent12.180.00810.98232.73
≥37Present1.000.09470.94231.40
Strep B OIA in labor: negative<28Absent0.620.00810.0501.67
<28Present0.050.15260.0772.56
28–30Absent0.690.00340.0240.79
28–30Present0.060.05470.0311.03
31–33Absent1.620.00150.0250.82
31–33Present0.130.02100.0280.92
34–36Absent5.010.00070.0351.18
34–36Present0.410.00900.0371.23
≥37Absent69.170.00030.2207.33
≥37Present5.650.00390.2217.35
Strep B OIA in labor: positive<28Absent0.120.12640.1555.17
<28Present0.010.76080.0762.54
28–30Absent0.140.05720.0792.63
28–30Present0.010.50540.0571.90
31–33Absent0.320.02620.0842.81
31–33Present0.030.27430.0722.41
34–36Absent1.000.01230.1224.08
34–36Present0.080.13790.1123.74
≥37Absent13.750.00560.76825.58
≥37Present1.120.06470.72724.24
  • Abbreviations: GBS, group B streptococcus; PROM, prolonged rupture of membranes.