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. 2019 Sep 24;16(9):e1002913. doi: 10.1371/journal.pmed.1002913

Table 3. Maternal and perinatal outcomes following planned VBAC with and without labor induction compared to ERCS.

ERCS Planned VBAC without labor induction Planned VBAC with labor induction
n outcome events/total N (%) n outcome events/total N (%) Base model1 relative risk (95% CI) Model A2 relative risk (95% CI) Model B3
relative risk (95% CI)		 Model C4 relative risk (95% CI) n outcome events/ total N (%) Base model1 relative risk (95% CI) Model A2 relative risk (95% CI) Model B3
relative risk (95% CI)		 Model C4 relative risk (95% CI)
Maternal outcomes
Uterine rupture 17/45,579 (0.04) 53/23,119 (0.23) 5.92
(3.38–10.37)
p < 0.001 		5.89
(3.34–10.41)
p < 0.001 		6.85
(3.55–13.19)
p < 0.001 		- 16/5,245 (0.31) 7.89
(3.99–15.61)
p < 0.001 		8.17
(4.08–16.35)
p < 0.001 		10.06
(4.65–21.72)
p < 0.001 		-
Peripartum hysterectomy 19/45,579 (0.04) #
(0.02)		 0.39
(0.13–1.12)
p = 0.080		 NC NC - # 0.85
(0.20–3.64)
p = 0.828		 NC NC -
Blood transfusion† 226/45,579 (0.50) 256/23,119 (1.11) 2.06
(1.72–2.47)
p < 0.001 		2.04
(1.70–2.45)
p < 0.001 		2.22
(1.81–2.72)
p < 0.001 		- 68/5,245 (1.30) 2.42
(1.83–3.19)
p < 0.001 		2.38
(1.81–3.14)
p < 0.001 		2.67
(1.99–3.58)
p < 0.001 		-
Puerperal sepsisഠ78/45,579 (0.17) 54/23,119 (0.23) 1.51
(1.06–2.14)
p = 0.021 		1.48
(1.04–2.10)
p = 0.028 		1.60
(1.07–2.39)
p = 0.021 		- 21/5,245 (0.40) 2.55
(1.56–4.16)
p < 0.001 		2.49
(1.53–4.06)
p < 0.001 		2.59
(1.52–4.44)
p < 0.001 		-
Other puerperal infectionഠ1,016/45,579 (2.23) 524/23,119 (2.27) 0.98
(0.88–1.10)
p = 0.757		 0.97
(0.87–1.09)
p = 0.639		 1.19
(1.06–1.34)
p = 0.035 		- 135/5,245 (2.57) 1.10
(0.91–1.32)
p = 0.325		 1.08
(0.90–1.30)
p = 0.415		 1.34
(1.11–1.62)
p = 0.027 		-
Surgical injury 40/45,579 (0.09) 42/23,119 (0.18) 2.12
(1.38–3.25)
p < 0.001 		2.17
(1.42–3.32)
p < 0.001 		3.10
(1.91–5.04)
p < 0.001 		- # 1.33
(0.56–3.15)
p = 0.518		 1.37
(0.58–3.26)
p = 0.470		 2.22
(0.90–5.47)
p = 0.082		 -
Length of postnatal hospital stay > 5 days†‡¥ 1,410/45,579 (3.09) 672/23,119 (2.91) 0.83
(0.76–0.92)
p < 0.001 		0.84
(0.77–0.93)
p = 0.001 		0.93
(0.83–1.04)
p = 0.120		 - 202/5,245 (3.85) 1.11
(0.96–1.30)
p = 0.167		 1.11
(0.95–1.29)
p = 0.189		 1.15
(0.97–1.35)
p = 0.099		 -
Readmission to hospital within 42 days of birtha†‡¥ 1,332/45,577 (2.92) 531/23,118 (2.30) 0.81
(0.73–0.89)
p < 0.001 		0.80
(0.72–0.89)
p < 0.001 		0.88
(0.78–0.98)
p = 0.024 		- 176/5,245 (3.36) 1.19
(1.01–1.39)
p = 0.036 		1.18
(1.00–1.38)
p = 0.045 		1.20
(1.01–1.42)
p = 0.035 		-
Any breastfeeding at birth or hospital dischargeb 21,403/39,297 (54.46) 12,187/19,083 (63.86) 1.19
(1.17–1.20)
p < 0.001 		1.19
(1.17–1.21)
p < 0.001 		1.18
(1.16–1.20)
p < 0.001 		1.15
(1.13–1.17)
p < 0.001 		2,664/4,292 (62.07) 1.15
(1.12–1.18)
p < 0.001 		1.20
(1.17–1.23)
p < 0.001 		1.17
(1.14–1.21)
p < 0.001 		1.13
(1.09–1.16)
p < 0.001
Exclusive breastfeeding at 6–8 week reviewc 9,788/39,251 (24.94) 6,720/19,531 (34.41) 1.38
(1.34–1.42)
p < 0.001 		1.39
(1.36–1.43)
p < 0.001 		1.38
(1.34–1.42)
p < 0.001 		1.32
(1.28–1.36)
p < 0.001 		1,339/4,471 (29.9) 1.20
(1.14–1.26)
p < 0.001 		1.29
(1.24–1.35)
p < 0.001 		1.33
(1.26–1.41)
p < 0.001 		1.22
(1.16–1.30)
p < 0.001
Any breastfeeding at 6–8 week reviewc 13,556/39,251 (34.54) 8,663/19,531 (44.36) 1.29
(1.26–1.32)
p < 0.001 		1.29
(1.27–1.32)
p < 0.001 		1.29
(1.26–1.32)
p < 0.001 		1.25
(1.22–1.28)
p < 0.001 		1,788/4,471 (40.24) 1.17
(1.13–1.22)
p < 0.001 		1.25
(1.21–1.30)
p < 0.001 		1.28
(1.22–1.34)
p < 0.001 		1.20
(1.14–1.25)
p < 0.001
Perinatal outcomesd
Adverse perinatal outcomee†‡¥ 2,570/40,369 (6.37) 1,583/20,878 (7.58) 1.15
(1.08–1.23)
p < 0.001 		1.16
(1.08–1.24)
p < 0.001 		1.30
(1.20–1.39)
p < 0.001 		1.49
(1.38–1.60)
p < 0.001 		458/4,724 (9.70) 1.51
(1.36–1.68)
p < 0.001 		1.49
(1.34–1.66)
p < 0.001 		1.56
(1.40–1.75)
P<0.001 		2.00
(1.78–2.25)
p < 0.001
Intrapartum stillbirth or neonatal death 5/45,567 (0.01)

(0.07)		 6.9
(2.48–19.19)
p < 0.001 		NC NC NC #
(0.06)		 5.35
(1.29–22.12)
p = 0.021 		NC NC NC
Admitted to a neonatal unit†‡¥ 2,377/45,062 (5.27) 1,171/22,645 (5.17) 0.94
(0.88–1.02)
p = 0.126		 0.95
(0.88–1.02)
p = 0.182		 1.07
(0.99–1.16)
p = 0.083		 1.24
(1.15–1.35)
p < 0.001 		340/5,136 (6.62) 1.23
(1.09–1.39)
p < 0.001 		1.21
(1.08–1.37)
p = 0.002 		1.27
(1.12–1.45)
p < 0.001 		1.66
(1.46–1.89)
p < 0.001
Resuscitation requiring drugs and/or intubation†‡¥ 133/40,830 (0.33) 335/21,405 (1.57) 4.69
(3.83–5.75)
p < 0.001 		4.72
(3.85–5.78)
p < 0.001 		5.30
(4.24–6.62)
p < 0.001 		5.34
(4.27–6.68)
p < 0.001 		91/4,824 (1.89) 5.66
(4.32–7.40)
p < 0.001 		5.59
(4.27–7.33)
p < 0.001 		6.17
(4.60–8.27)
p < 0.001 		6.27
(4.66–8.45)
p < 0.001
Apgar score < 7 at 5 minutes†‡¥ 192/45,194 (0.42) 309/22,807 (1.35) 3.24
(2.70–3.88)
p < 0.001 		3.26
(2.72–3.91)
p < 0.001 		3.50
(2.85–4.29)
p < 0.001 		3.66
(2.99–4.50)
p < 0.001 		95/5,190 (1.83) 4.39
(3.43–6.62)
p < 0.001 		4.31
(3.37–5.53)
p < 0.001 		4.47
(3.41–5.86)
p < 0.001 		4.87
(3.69–6.43)
p < 0.001

Bold text indicates statistically significant findings at the 5% level.

1 Base model adjusted for year of delivery.

2 Model A adjusted for year of delivery and sociodemographic factors (maternal age, mother’s country of birth, marital status/registration type, and socioeconomic status).

3 Model B adjusted for variables in model A and additionally adjusted for maternal medical and pregnancy-related factors (number of previous cesarean sections, any prior vaginal delivery, interpregnancy interval, maternal smoking status at booking, maternal BMI at booking, hypertensive disorder where † is shown, diabetes where ‡ is shown, and prelabor rupture of membranes where ¥ is shown).

4 Model C adjusted for variables in model B and additionally adjusted for infant-related factors (sex of infant, gestational age at delivery, and birth weight centile).

aWomen who died before discharge or were not discharged within 42 days of birth were excluded from analysis of overnight readmission to hospital (n = 3).

bIntrapartum stillbirths (n = 6) and births missing data on feeding at birth and hospital discharge (n = 11,265, 15.2%) were excluded from analysis of breastfeeding at birth or hospital discharge.

cIntrapartum stillbirths (n = 6), neonatal deaths (46), and births missing infant feeding data at 6–8 week review (n = 10,638, 14.4%) were excluded from analysis of breastfeeding outcomes at 6–8 weeks.

dAll perinatal outcomes exclude deaths because of congenital abnormalities (n = 27) and any remaining intrapartum stillbirths (n = 5) and births missing the outcome in question (n = 1,068, 1.4% for admission to a neonatal unit; n = 6,852, 9.3% for resuscitation; n = 720, 1.0% for Apgar score) were additionally excluded from analysis of neonatal unit admission, resuscitation, and Apgar score.

eIncludes intrapartum stillbirth or neonatal death, admission to a neonatal unit, resuscitation requiring drugs, and/or intubation or an Apgar score < 7 at 5 minutes.

#Numbers or numbers and percentages have not been shown to protect against potential disclosure risks.

Abbreviations: CI, confidence interval; ERCS, elective repeat cesarean section; NC, not calculated because of low number of events; VBAC, vaginal birth after previous cesarean