Factors Associated with Successful Vaginal Birth After a Primary Cesarean Section in Women with an Optimal Inter-Delivery Interval

Figures & data

Table 1 Sample and Maternal Characteristics Stratified by Success or Failure of Vaginal Birth After Cesarean (VBAC)

Characteristic	Overall Sample N=231 n (%)	Failed VBAC N=98 n (%)	Successful VBAC N=133 n (%)	P-value
Age (years) – mean ± SD	28.7 ± 5.8	28.3 ± 5.7	28.9 ± 5.8	0.409
≤20	20 (8.7)	10 (10.2)	10 (7.5)
21–25	56 (24.2)	21 (21.4)	35 (26.3)
26–30	69 (29.9)	40 (40.8)	29 (21.8)
31–40	81 (35.1)	24 (24.5)	57 (42.9)
≥41	5 (2.2)	3 (3.1)	2 (1.5)
Parity (median, IQR)	4 (2–6)	3 (2–5)	4 (3–6)	0.002
Prior Vaginal Delivery	159 (68.8)	59 (60.2)	100 (75.2)	0.021
Inter-delivery interval				0.228
18–23	75 (32.6)	32 (32.7)	43 (32.6)
24–35	97 (42.2)	35 (35.7)	62 (47.0)
36–47	34 (14.8)	17 (17.3)	17 (12.9)
48–59	13 (5.7)	8 (8.2)	5 (3.8)
60–71	11 (4.8)	6 (6.1)	5 (3.8)
Occupation				0.428
Household	165 (71.4)	65 (66.3)	100 (75.2)
Farmer	20 (8.7)	9 (9.2)	11 (8.3)
Commercial	19 (8.2)	9 (9.2)	10 (7.5)
Other	27 (11.7)	15 (15.3)	12 (9.0)
Marital status				0.653
Single	11 (4.8)	4 (4.1)	7 (5.3)
Married	216 (93.5)	92 (93.9)	124 (93.2)
Divorced	1 (0.4)	0 (0)	1 (0.8)
Widow	3 (1.3)	2 (2.0)	1 (0.8)
Residence				0.648
Bagira	13 (5.6)	7 (7.1)	6 (4.5)
Ibanda	126 (54.5)	56 (57.1)	70 (52.6)
Kadutu	43 (18.6)	16 (16.3)	27 (20.3)
Rural	49 (21.2)	19 (19.4)	30 (22.6)

Notes: P-values are shown in bold for statistically significant characteristics.

Abbreviations: SD, standard deviation; IQR, inter-quartile range; VBAC, vaginal birth after cesarean.

Table 2 Indication for Primary Cesarean Section, Stratified by Delivery Mode

Indication	Overall Sample N=231 n (%)	Failed VBAC N=98 n (%)	Successful VBAC N=133 n (%)	P-value
Cervical dystocia	16 (6.9)	10 (10.2)	6 (4.5)	0.117
Obstructed labor	3 (1.3)	0 (0)	3 (2.3)	0.264
Fetal distress	80 (34.6)	33 (33.7)	47 (35.3)	0.889
Severe preeclampsia	6 (2.6)	4 (4.1)	2 (1.5)	0.405
Malpresentation	44 (19.0)	14 (14.3)	30 (22.6)	0.129
Placenta previa	13 (5.6)	5 (5.1)	8 (6.0)	0.999
Elective	2 (0.9)	0 (0)	2 (1.5)	0.509
Unknown	67 (29.0)	32 (32.7)	35 (26.3)	0.308

Abbreviation: VBAC, vaginal birth after cesarean.

Table 3 Indication for Repeat Cesarean Section (RCS)

Indication	Overall N=98 n (%)
Cephalopelvic disproportion	22 (22.4)
Requested CS during TOL	15 (15.3)
Fetal distress	20 (20.4)
Malpresentation	11 (11.2)
Failure to progress	30 (30.6)

Abbreviations: CS, cesarean section; TOL, trial of labor.

Table 4 Obstetrical and Neonatal Characteristics Stratified by Success or Failure of Vaginal Birth After Cesarean (VBAC)

Characteristic	Overall Sample N=231 n (%)	Failed VBAC N=98 n (%)	Successful VBAC N=133 n (%)	P-value
Gestational age (weeks) – mean ± SD	38.6 ± 2.0	38.5 ± 2.0	38.7 ± 2.1	0.454
Actual fetal weight (kg) – mean ± SD	3.09 ± 0.47	3.20 ± 0.53	3.02 ± 0.40	0.004
Fetal macrosomia	25 (10.8)	19 (19.4)	6 (4.5)	≤.001
Uterine height (m) – mean ± SD	0.31 ± 0.03	0.32 ± 0.03	0.30 ± 0.02	≤.001
Spontaneous labor onset	184 (79.7)	68 (69.4)	116 (87.2)	0.001
Oxytocin use	50 (21.6)	23 (23.5)	27 (20.3)	0.629
Bishop Score (median, IQR)	11 (8–12)	10 (6–12)	11 (9–12)	0.002

Notes: P-values are shown in bold for statistically significant characteristics.

Abbreviations: SD, standard deviation; kg, kilogram; m, meter; IQR, inter-quartile range; VBAC, vaginal birth after cesarean.

Table 5 Factors Associated with a Successful Vaginal Birth After Cesarean (VBAC)

Factors	OR (95% CI)	AOR (95% CI)
Maternal age	1.02 (0.97, 1.07)	0.98 (0.92, 1.05)
Parity	1.15 (1.02, 1.29)	1.09 (0.92, 1.29)
Prior vaginal delivery	2.00 (1.14, 3.52)	1.49 (0.76, 2.94)
Fetal macrosomia	0.20 (0.08, 0.51)	0.21 (0.08, 0.58)
Spontaneous labor onset	3.01 (1.55, 5.86)	3.06 (1.52, 6.17)
Bishop score	1.13 (1.04, 1.24)	1.12 (1.02, 1.23)

Notes: Statistically significant factors are shown in bold.

Abbreviations: OR, odds ratio; AOR, adjusted odds ratio; CI, confidence interval.