A Prognostic Study for the Development of Risk Prediction Model for the Success of Vaginal Birth Following a Cesarean Surgery at Felege Hiwot Comprehensive Specialized Hospital, Northwest Ethiopia

Figures & data

Figure 1 Schematic representation of sampling technique at FHCSH Northeast Ethiopia.

Table 1 Societal and Demographic Characteristics of Mothers, Who Was Candidate for VBAC, Gave Birth at FHCSH from January 30/2017 to January 30/2021

Variable	Category	Frequency	Percent(N=700)
Age	>35 yrs.	107	15.3
	<=35 yrs.	593	84.7
Marital status	Married	679	97
	Un married	21	3
Educational status	≥9	579	82.7
	<9	121	17.3

Table 2 Current and Past Obstetric-Related Factors of Mothers Who Gave Birth by VBAC at FHCSH from January 30/2019 to January 30/2021

Variables	Category	Frequency	Percent
Parity	Primiparity	33	4.7
	Multipara	667	95.3
History of vaginal birth	Yes	258	79.9
	No	442	19.1
History of successful VBAC	Yes	44	36.9
	No	656	63.1
Previous cesarean indication	Recurrent	128	18.3
	Non recurrent	572	81.7
Oxytocin augmentation	Yes	29	4.1
	No	671	95.9
Bishop score	>5	222	32.7
	<5	478	68.3
Place of ANC	Health centers	619	88.4
	Hospitals	81	11.6
Initiation time of ANC	First trimester	170	24.3
	Second trimester	530	75.7
Rupture of membrane	Ruptured	136	19.4
	Intact	564	89.6
Onset of labor	Spontaneous	186	26.7
	Induced	514	83.3
Estimated fetal weight	>4 kg	337	48.1
	<=4 kg	365	51.9
Gestational age	37–39 wks	542	77.4
	≥40 wks	158	22.6

Table 3 Analysis of Bivariable logistic Regression to Construct a VBAC Prediction Model

Variables	Category	VBAC		COR	95% CI	P-value
		Yes	No
History of vaginal birth	Yes	328	141	3.117	(2.10,4.84)	0.005
	No	28	203	1
History of VBAC	Yes	188	70	1.539	(1.10,2.15)	<0.001
	No	281	161	1
Chronic disease	No	8	19	5.165	(2.22,11.98)	0.001
	Yes	461	212	1
Estimated fetal weight	<=4 kg	296	117	1.311	(0.95,1.79)	<0.01
	>4 kg	200	114	1
Rupture of membrane	Intact	122	14	5.45	(3.05,9.71)	<0.001
	Ruptured	347	217	1
Bishop score	> 5	183	39	3.15	(2.13,4.65)	< 0.001
	<=5	192	286	1
Initiation of ANC	First trimester	38	6	0.71	(−31, 1.73)	0.16
	Second trimester	431	225	1
Oxytocin	Yes	14	15	2.275	(1.07,4.76)	0.16
	No	455	226
Parity	Multipara	14	19	2.913	(1.43, 5.92)	<0.003
	Primiparity	455	212	1
Onset of labor	Spontaneous	160	26	4.083	(2.60,6.40)	0.01
	Induced	309	205
Time from previous delivery	>2 yrs	99	10	5.017	(2.75,9.13)	<0.04
	<=2 yrs	370	10	1
Gestational Age	37–39 wks	116	42	1.479	(0.97,2.19)	0.019
	≥40 wks.	353	138	1

Table 4 Each Predictor’s Risk Scores and Coefficients Were Incorporated in the Model to Predict VBAC (n = 700)

Predictors Variables	Multivariable Analysis
	Original β (95% CI)	Bootstrap β	P-value		Risk Score
Time from previous delivery (>2yrs)
	1.761 (1.134, 2.512)	1.708	<0.001		3
Hx of successful VBAC (yes)	1.137 (0.211, 2.222)	1.084	0.020		2
Rupture of membrane (ruptured)	1.495 (0.9186, 2.140)	1.471	<0.013		3
Parity (multi-Para)	1.199 (0.405, 2.028)	1.176	<0.001		2
Onset of labor(spontaneous)	1.265 (0.799, 1.763)	1.152	<0.020		2
ANC initiation time (first TMR)	0.605 (0.135, 1.094)	0.593	<0.001		1

Notes: Linear predictors for the predicted likelihood that a VBAC will be successful = 1/ (1 + exp – (1.266 + 1.762 * time from previous delivery (>2 yrs) + 1.137 *previous history of successful VBAC (yes) + 1.495*rupture of membrane (ruptured) + 1.199*parity (multipara) +1.265* onset of labor (spontaneous) + 0.604*time of initiation of ANC follow up (second TMR).

Figure 2 Area under the ROC curve for the prediction model success of VBAC.

Figure 3 ROC (AUC) of risk prediction model after bootstrapping for success of VBAC among mothers who gave birth at FHCSH.

Figure 4 Predicted versus observed preterm birth probability in the sample. Calibration plot created using “givitiCalibrationBelt” in R programming.

Figure 5 A decision curve plotting the net benefit of the model against threshold probability.

Table 5 Utilizing a Streamlined Prediction Score, Classify the Risk of Successful VBAC (n = 700)

Score*(Risk Category)	Model for Prediction Using Maternal Factors
	Mothers in Number	Incidence of Success of VBAC
<3 (Low)	368 (52.57%)	185 (49.7%)
≥3 (High)	332 (47.4%)	284 (85.5%)