Table 1 Antepartum characteristics of nulliparous undergoing induction of labor at term

Maternal age (y)

28.4 ± 3.1

28.6 ± 3.0

0.016

Weight (kg)

71.0 ± 9.3

71.2 ± 9.1

0.431

Height (cm)

162.0 ± 4.5

161.9 ± 4.6

0.742

Uterine height (cm)

35.5 ± 2.2

35.4 ± 2.2

0.032

Abdominal circumference (cm)

101.3 ± 6.3

101.2 ± 6.1

0.780

Gestational age (wk)

39 (39-41)

40 (39-41)

0.007

Fetal sex

0.585

 Male

1542 (52.3)

996 (51.5)

 Female

1408 (47.7)

939 (48.5)

Estimated fetal weight (g)

3500 (3200-3600)

3500 (3200-3600)

0.270

Initial cervical dilation (cm)

0.002

 0 (0 points)

2880 (97.6)

1913 (98.9)

 1-2 (1 points)

70 (2.4)

22 (1.1)

Initial station

0.106

 -3 (0 points)

962 (65.5)

583 (30.1)

 -2 (1 points)

1932 (32.6)

1322 (68.3)

 -1 or 0 (2 points)

56(1.9)

30 (1.6)

 + 1 (3 points)

–

–

Initial cervical effacement (%)

<0.001

 0-30 (0 points)

5 (0.2)

2 (0.1)

 40-50 (1 points)

520 (17.6)

256 (13.2)

 60-70 (2 points)

2205 (74.7)

1492 (77.1)

 ≥ 80 (3 points)

220 (7.5)

185 (9.6)

Initial cervical position

<0.001

 Posterior (0 points)

1015 (34.4)

570 (29.5)

 Mid position (1 points)

1875 (63.6)

1352 (69.9)

 Anterior (2 points)

60 (2.0)

13 (0.7)

Initial cervical consistency

<0.001

 Firm (0 points)

44 (1.5)

17 (0.9)

 Medium (1 points)

1495 (50.7)

1102 (57.0)

 Soft (2 points)

1411 (47.8)

816 (42.2)

Bishop Score

5 (4-5)

5 (4-5)

0.621

 <6

2185 (74.1)

1421 (73.4)

 ≥ 6

765(25.9)

514 (26.6)

Indications for induction of labor

<0.001

 PROM

1319 (44.8)

941 (48.6)

 Late term (41 weeks or greater)

779 (26.4)

522 (27.0)

 Diabetes mellitus

472(16.0)

167 (8.6)

 Hypertensive disorder of pregnancy

81 (2.7)

108 (5.6)

 Others

299 (10.1)

197(10.2)

Cesarean delivery

392 (13.3)

317 (16.4)