Elevated resting tonea N= 567 Normal resting tone N= 1643
p-value
Labor characteristics
     Induction of labor 300 (52.9) 992 (60.4) <0.01
     Artificial rupture of membranes 391 (69.0) 1,161 (70.7) 0.44
     Oxytocin use 476 (84.0) 1475 (89.8) <0.01
          Maximum oxytocin dose 12 (6-18) 14 (8-20) <0.01
          High dose oxytocin (>20 mu/min) 100 (21.0) 395 (25.8) 0.01
     Prostaglandin use 124 (21.9) 363 (22.1) 0.91
     Magnesium use 50 (8.8) 143 (8.7) 0.93
     Chorioamnionitis 35 (6.2) 61 (3.7) 0.01
     Terbutaline 25 (4.4) 85 (5.2) 0.47
Labor Length (hrs) 12.1 (8.2-16.8) 12.5 (8.7-18.3) 0.07
     Duration of 1st stage (hrs) 10.0 (6.4-15.0) 11.0 (7.3-16.4) <0.01
     Duration of 2nd stage (min) 29 (16-54) 26 (13-51) 0.02
Labor duration >24hrs 57 (10.1) 182 (11.1) 0.51
Prolonged 2nd stage (≥3hrs) 19 (3.4) 36 (2.2) 0.15
Tachysystole in last 30 minutes 87 (15.3) 22 (1.3) <0.01
Mode of delivery Spontaneous vaginal Operative vaginal Cesarean delivery 527 (93.0) 38 (6.7) 2 (0.4) 1490 (90.7) 113 (6.9) 40 (2.4)
<0.01
aElevated tone defined as > 75th percentile *Data presented as N(%), Mean ± SD, or Median (IQR) aElevated tone defined as > 75th percentile *Data presented as N(%), Mean ± SD, or Median (IQR) aElevated tone defined as > 75th percentile *Data presented as N(%), Mean ± SD, or Median (IQR) aElevated tone defined as > 75th percentile *Data presented as N(%), Mean ± SD, or Median (IQR)