Keywords
trial of labor after cesarean - vaginal birth after cesarean - hispanic - Latina -
ethnicity
The rate of cesarean delivery in the United States has increased from 5% in 1970 to
31.9% in 2016.[1] Offering a trial of labor after cesarean section (TOLAC) is one strategy to help
reduce the rate of cesarean delivery. However, the overall morbidity and mortality
associated with cesarean delivery in the setting of failed TOLAC is higher than the
overall morbidity and mortality associated with elective repeat cesarean delivery.
Different tools have been developed to help obstetricians predict the chances of successful
vaginal birth after cesarean (VBAC) and to facilitate shared decision-making with
patients regarding TOLAC versus elective repeat cesarean delivery. One of the most
widely recognized prediction models is the VBAC calculator developed in 2007 by the
National Institute of Child Health and Human Development. Maternal–Fetal Medicine
Units Network (MFMU) based on observational data published in 2005.[2]
[3] This prediction model was subsequently expanded in 2009 to include additional information
available at the time of admission.[4] Both the original 2007 prediction model and the expanded 2009 prediction model identified
“Hispanic” or “Latina” ethnicity as a negative predictive factor, based on an n = 2,362 Latinas (19.9% of the MFMU study population). In 2006 Hollard et al came
to a similar conclusion that Latinas are significantly less likely than Caucasian
women to achieve successful VBAC, based on a study that included n = 993 Latinas (39% of the study population).[5]
More recently in 2017, Maykin et al. performed a retrospective cohort study on an
ethnically diverse population in which Latinas outnumbered any other ethnic group
(n = 229 Latinas, 40.3% of the study population).[6] This study categorized patients into one of three groups based on the percent chance
of VBAC success: “low” if their predicted success was <35%, “moderate” if their predicted
success was 35 to 65%, and “high” if their predicted success >65%. The majority of
Latinas in the study fell into the low (<35%) predicted success group. In contrast
to prior studies, Maykin et al. observed that the MFMU prediction model underestimated
the likelihood of VBAC success for patients in the low (<35%) predicted success group
and concluded that ethnicity is not predictive of VBAC success.
A recent commentary in Obstetrics & Gynecology regarding disparities in women's health suggests that race has been “historically
mishandled” in research and clinical care due to the presumption that race alone implies
a biologic difference.[7] We suspected that for our study population residing in East Los Angeles, there may
be similar complexities in using “Latina” ethnicity as an a priori negative factor for predicting VBAC success. The objective of our study was to compare
predicted VBAC success rates according to the MFMU prediction model with the observed
VBAC success rates in an exclusively Latina patient population.
Materials and Methods
The western Institutional Review Board approved this study which was conducted at
Adventist Health White Memorial (AHWM). AHWM is a teaching hospital in inner-city
Los Angeles with a predominantly Latina patient population. A total of 15,245 deliveries
occurred at AHWM from January 1, 2013 to December 31, 2016. All 701 women who attempted
TOLAC at AHWM within this time frame were identified through a review of the Obstetrics/Gynecology
Department's archive of statistical data forms for each delivery. Each patient's ethnicity
was based on self-reported information at the time of admission. 95% of our TOLAC
patients during the study period were Latina; only 5% of all TOLAC patients identified
themselves as Caucasian, African American, Asian, or other ethnicity and were excluded
from analysis. The following Latina TOLAC patients were also excluded: <18 years of
age, preterm (<37 weeks of gestational age), fetal demise, lethal fetal anomalies,
deliveries at home or in transit to the hospital, precipitous deliveries upon arrival
or shortly thereafter, incomplete medical records, and laboring patients who requested
to stop TOLAC and proceed with elective repeat cesarean delivery. [Fig. 1] depicts a flow diagram of the final study population after exclusions were made.
Patients with two prior cesarean deliveries were not excluded because the prediction
model has been validated by Metz et al. (2015) for women with two prior cesarean sections.[8]
Fig. 1 Flow chart of study participants, exclusions, and final classification based on predicted
success. TOLAC, trial of labor after cesarean; VBAC, vaginal birth after cesarean.
To calculate the chance of successful VBAC for each patient using the MFMU prediction
model, the following patient characteristics on admission were obtained from medical
records: age, height, weight, body mass index (BMI), ethnicity, any prior vaginal
delivery, any prior VBAC, indication for prior cesarean delivery, estimated gestational
age at delivery, dilation, effacement, station, whether the patient had hypertensive
disease of pregnancy, and whether labor was induced or spontaneous. A comparison of
our study cohort characteristics to the 2007 MFMU cohort characteristics is described
in [Table 1].
Table 1
A Comparison of the 2007 maternal–fetal medicine units cohort to the current study
cohort
|
Variable
|
2007 MFMU cohort
|
Current study cohort
|
|
Average maternal age (y)
|
28.6 ± 5.8
|
29.3 ± 5.6
|
|
Average BMI (kg/m2)
|
26.4 ± 6.3
|
33.7 ± 6.1
|
|
Prior cesarean delivery for arrest of dilation or arrest of descent
|
4,108 (36.3%)
|
224 (39.5%)
|
|
Any prior vaginal delivery
|
5,617 (47.5%)
|
262 (46.2%)
|
|
Vaginal delivery after prior cesarean
|
3,996 (33.7%)
|
164 (28.9%)
|
|
Pre-existing diabetes
|
99 (0.84%)
|
12 (2.1%)
|
|
Latinas
|
2,362 (19.9%)
|
567 (100%)
|
Abbreviation: BMI, body mass index; MFMU, maternal–fetal medicine units.
We extracted the following data from the medical records for each patient: maternal
comorbidities prior to labor onset (chronic hypertension and pregestational and gestational
diabetes), intrapartum information (augmentation of labor with oxytocin, epidural
use, and administration of magnesium sulfate), neonatal information (gestational age
at delivery, birth weight, and 5-minute Apgar's score), and peripartum complications
(gestational hypertension and preeclampsia, chorioamnionitis, endometritis, uterine
rupture, postpartum hemorrhage, and cesarean hysterectomy). In our study, uterine
rupture is defined as a complete separation of the scar seen intraoperatively, with
clinical signs and symptoms suspicious for rupture prior to surgery. Postpartum hemorrhage
is defined as blood loss ≥500 ccs for vaginal delivery or ≥1,000 ccs for cesarean
delivery.
The MFMU prediction model was used to calculate each patient's probability of VBAC
success. As in the study by Maykin et al., our study participants were assigned to
one of three groups based on the percent chance of VBAC success: “low” if their predicted
success was <35%, “moderate” if their predicted success was 35 to 65%, and “high”
if their predicted success >65%.
All statistical analyses and testing were performed using SAS software. For continuous
variables such as maternal age or BMI, p-values were generated through analyses of variance. Values for categorical variables
were calculated with the Chi-square statistic; when approximately 50% of the cells
had expected counts of less than 5, the Chi-square was replaced with Fisher's exact
test (two-sided). When too many cells had expected counts of less than 5, statistical
testing was not performed and p-values were not noted in the tables. For all other variables, we presented the actual
calculated p-value, with a lower bound of 0.001 (any lower values were represented as <0.001).
Results
Of the 701 women who attempted TOLAC at AHWM during the study period, 662 were Latina
and 567 of these Latina TOLAC patients were eligible for analysis ([Fig. 1]). Within the total cohort of 567 Latinas undergoing TOLAC, 476 (84.0%) successfully
achieved VBAC and 91 (16.0%) failed TOLAC.
A comparison of variables between the 476 patients who achieved VBAC and the 91 patients
who failed TOLAC is summarized in [Table 2]. The successful VBAC group and the failed TOLAC group were similar in terms of rates
of advanced maternal age, hypertensive disease, epidural use, and intrapartum magnesium
use. However, Latina patients who failed TOLAC were more likely to have the following
characteristics: obesity, diabetes, prior cesarean delivery for arrest of dilation
or descent, and induced labor. Latinas who failed TOLAC were also more likely to experience
chorioamnionitis. There were not enough cases of endometritis or 5-minute Apgar's
score <7 to make statistically meaningful comparisons between the two groups. Overall,
the majority of negative predictive factors in the MFMU prediction model (i.e., obesity,
prior cesarean delivery for arrest of dilation or descent, and induced labor) were
also relevant in our Latina patient population.
Table 2
Characteristics of successful vaginal birth after cesarean group compared with characteristics
of failed trial of labor after cesarean group
|
VBAC
(n = 476)
|
|
Failed TOLAC
(n = 91)
|
|
Total
(n = 567)
|
|
p-Value
|
|
Advanced maternal age (≥35 years)
|
89
|
18.70%
|
10
|
10.99%
|
100
|
17.46%
|
0.076
|
|
BMI ≥30 kg/m2
|
339
|
71.22%
|
76
|
83.52%
|
416
|
73.19%
|
0.015
|
|
Indication for prior cesarean
|
|
Arrest of dilation or descent
|
175
|
36.76%
|
49
|
53.85%
|
224
|
39.51%
|
0.002
|
|
Other (e.g., nonreassuring FHT, nonvertex)
|
301
|
63.24%
|
42
|
46.15%
|
346
|
60.49%
|
|
Labor type
|
|
Spontaneous
|
402
|
84.45%
|
62
|
68.13%
|
466
|
81.83%
|
<0.001
|
|
Induction
|
74
|
15.55%
|
29
|
31.87%
|
104
|
18.17%
|
<0.001
|
|
Augmentation
|
212
|
44.54%
|
41
|
45.05%
|
255
|
44.62%
|
0.928
|
|
Comorbidities
|
|
Hypertensive disease of pregnancy
|
36
|
7.56%
|
10
|
10.99%
|
47
|
8.11%
|
0.273
|
|
Diabetes
|
48
|
10.08%
|
18
|
19.78%
|
66
|
11.64%
|
0.008
|
|
Intrapartum variables
|
|
Cervical ripening balloon
|
45
|
9.45%
|
23
|
25.27%
|
69
|
11.99%
|
<0.001
|
|
Labor epidural
|
363
|
76.42%
|
71
|
78.02%
|
437
|
76.68%
|
0.741
|
|
Magnesium
|
20
|
4.21%
|
6
|
6.59%
|
27
|
4.59%
|
0.286
|
|
Perinatal outcomes
|
|
Chorioamnionitis
|
45
|
9.45%
|
16
|
17.58%
|
61
|
10.76%
|
0.022
|
|
5-minute Apgar's score < 7
|
2
|
0.42%
|
3
|
3.30%
|
5
|
0.88%
|
0.031
|
|
Endometritis
|
1
|
0.21%
|
2
|
2.20%
|
3
|
0.53%
|
0.069
|
|
Uterine rupture
|
0
|
0.00%
|
3
|
3.30%
|
3
|
0.53%
|
0.004
|
|
Postpartum hemorrhage
|
23
|
4.83%
|
1
|
1.10%
|
24
|
4.23%
|
0.152
|
Abbreviations: FHT, fetal heart tracing; TOLAC, trial of labor after cesarean; VBAC,
vaginal birth after cesarean.
The individual predicted VBAC success rates for our Latina TOLAC patients ranged from
5.0 to 94.0% ([Fig. 1] and [Tables 3–5]). The 95 patients in the “low” (<35%) predicted success group had an actual VBAC
success rate of 65.3%. The 256 patients in the “moderate” (35–65%) predicted success
group had an actual VBAC success rate of 84.4%. The 216 patients in the “high” (>65%)
predicted success group had an actual VBAC success rate of 91.7%. Statistically significant
differences were noted when comparing the three predicted success groups in terms
of demographics and obstetrical histories ([Table 3]), intrapartum variables and comorbidities ([Table 4]), and perinatal outcomes ([Table 5]). The trends in these variables among the three predicted success groups were expected,
given that the three groups were defined by these exact variables which are inherent
in the MFMU prediction model.
Table 3
Demographics and obstetrical history compared among the three predicted success groups
|
Group
|
Low
(n = 95)
|
|
Moderate
(n = 256)
|
|
High
(n = 216)
|
|
Total
(n = 567)
|
|
p-Value
|
|
Predicted success
|
<35%
|
|
35–65%
|
|
>65%
|
|
|
|
|
|
Maternal age
|
28.5 ± 4.7
|
|
28.6 ± 5.7
|
|
30.5 ± 5.5
|
|
29.3 ± 5.6
|
|
<0.001
|
|
BMI (kg/m2)
|
37.7 ± 7.7
|
|
33.0 ± 5.3
|
|
32.9 ± 5.7
|
|
33.7 ± 6.1
|
|
<0.001
|
|
Gravidity
|
2.6 ± 0.9
|
|
3.0 ± 1.5
|
|
4.1 ± 1.5
|
|
3.4 ± 1.5
|
|
<0.001
|
|
Parity
|
1.1 ± 0.6
|
|
1.5 ± 1.0
|
|
2.7 ± 1.1
|
|
1.9 ± 1.2
|
|
<0.001
|
|
Any prior vaginal delivery
|
3
|
3.16%
|
59
|
23.05%
|
200
|
92.59%
|
262
|
46.21%
|
<0.001
|
|
Prior VBAC
|
0
|
0.00%
|
17
|
6.64%
|
147
|
68.06%
|
164
|
28.92%
|
<0.001
|
|
Prior cesarean deliveries
|
|
1
|
95
|
100.0%
|
248
|
96.88%
|
208
|
96.30%
|
551
|
97.18%
|
0.178
|
|
2
|
0
|
0.00%
|
8
|
3.13%
|
8
|
3.70%
|
16
|
2.82%
|
|
|
Prior incision type
|
|
Low transverse ×1
|
42
|
44.21%
|
130
|
50.78%
|
70
|
32.41%
|
242
|
42.68%
|
<0.001
|
|
Unknown ×1
|
53
|
55.79%
|
118
|
46.09%
|
137
|
63.43%
|
308
|
54.32%
|
|
|
Low transverse ×2
|
0
|
0.00%
|
5
|
1.95%
|
4
|
1.85%
|
9
|
1.59%
|
|
|
Low transverse ×1
|
0
|
0.00%
|
0
|
0.00%
|
2
|
0.93%
|
2
|
0.35%
|
|
|
Unknown ×2
|
0
|
0.00%
|
3
|
1.17%
|
3
|
1.39%
|
6
|
1.06%
|
|
|
Indication for prior cesarean delivery
|
|
Arrest of dilation
|
63
|
66.32%
|
71
|
27.73%
|
41
|
18.98%
|
175
|
30.86%
|
<0.001
|
|
Arrest of descent
|
7
|
7.37%
|
30
|
11.72%
|
12
|
5.56%
|
49
|
8.64%
|
|
|
Nonreassuring fetal heart tracing
|
11
|
11.58%
|
58
|
22.66%
|
44
|
20.37%
|
113
|
19.93%
|
|
|
Malpresentation
|
6
|
6.32%
|
41
|
16.02%
|
56
|
25.93%
|
103
|
18.17%
|
|
|
Other
|
8
|
8.42%
|
56
|
21.88%
|
63
|
29.17%
|
127
|
22.40%
|
|
Abbreviations: BMI, body mass index; VBAC, vaginal birth after cesarean.
Table 4
Intrapartum variables and maternal comorbidities compared among the three predicted
success groups
|
Group
|
Low
(n = 95)
|
|
Moderate
(n = 256)
|
|
High
(n = 216)
|
|
Total
(n = 567)
|
|
p-Value
|
|
Predicted success
|
<35%
|
|
35–65%
|
|
>65%
|
|
|
|
|
|
Spontaneous labor
|
44
|
46.32%
|
217
|
84.77%
|
203
|
93.98%
|
464
|
81.83%
|
<0.001
|
|
Induction
|
51
|
53.68%
|
39
|
15.23%
|
13
|
6.02%
|
103
|
18.17%
|
<0.001
|
|
Augmentation
|
38
|
40.00%
|
133
|
51.95%
|
82
|
37.96%
|
253
|
44.62%
|
0.006
|
|
Labor epidural
|
84
|
88.42%
|
214
|
83.92%
|
136
|
62.96%
|
434
|
76.68%
|
<0.001
|
|
Cervical ripening balloon
|
40
|
42.11%
|
22
|
8.59%
|
6
|
2.78%
|
68
|
11.99%
|
<0.001
|
|
Intrapartum magnesium
|
10
|
10.53%
|
13
|
5.08%
|
3
|
1.40%
|
26
|
4.59%
|
<0.002
|
|
Diabetes
|
12
|
12.63%
|
30
|
11.72%
|
24
|
11.11%
|
66
|
11.64%
|
0.927
|
|
A1DM
|
5
|
5.26%
|
17
|
6.64%
|
21
|
9.72%
|
43
|
7.58%
|
0.370
|
|
A12DM
|
1
|
1.05%
|
7
|
2.73%
|
3
|
1.39%
|
11
|
1.94%
|
|
|
Class B DM
|
4
|
4.21%
|
6
|
2.34%
|
0
|
0.00%
|
10
|
1.76%
|
|
|
Class C DM
|
2
|
2.11%
|
0
|
0.00%
|
0
|
0.00%
|
2
|
0.35%
|
|
|
Hypertensive disease of pregnancy
|
22
|
23.16%
|
20
|
7.81%
|
4
|
1.85%
|
46
|
8.11%
|
<0.001
|
|
Chronic HTN
|
1
|
1.05%
|
4
|
1.56%
|
1
|
0.46%
|
6
|
1.06%
|
0.558
|
Abbreviations: DM, diabetes mellitus; HTN, hypertension.
Table 5
Perinatal outcomes compared among the three predicted success groups
|
Group
|
Low
(n = 95)
|
|
Moderate
(n = 256)
|
|
High
(n = 216)
|
|
Total
(n = 567)
|
|
p-Value
|
|
Predicted success
|
<35%
|
|
35–65%
|
|
>65%
|
|
|
|
|
|
VBAC
|
62
|
65.26%
|
216
|
84.38%
|
198
|
91.67%
|
476
|
83.95%
|
<0.001
|
|
5-minute Apgar's score < 7
|
1
|
1.05%
|
3
|
1.17%
|
1
|
0.46%
|
5
|
0.88%
|
0.715
|
|
Birth weight (g)
|
3,490 ± 436
|
|
3,363 ± 438
|
|
3,382 ± 474
|
|
3,382 ± 474
|
|
0.052
|
|
Chorioamnionitis
|
14
|
14.74%
|
36
|
14.06%
|
11
|
5.09%
|
61
|
10.76%
|
0.003
|
|
Endometritis
|
1
|
1.05%
|
2
|
0.78%
|
0
|
0.00%
|
3
|
0.53%
|
0.396
|
|
Uterine rupture
|
1
|
1.05%
|
2
|
0.78%
|
0
|
0.00%
|
3
|
0.53%
|
0.396
|
|
Postpartum hemorrhage
|
7
|
7.37%
|
10
|
3.91%
|
7
|
3.24%
|
24
|
4.23%
|
0.235
|
Abbreviation: VBAC, vaginal birth after cesarean.
Demographic information is summarized in [Table 3]. Patients with a low predicted success rate were younger (28.5 years) than patients
with moderate (28.6 years) and high (30.5 years) predicted success rates (p < 0.001). The low predicted success group also had a higher average BMI (37.7 kg/m2) than the moderate (33.0 kg/m2) and high (32.9 kg/m2) predicted success groups (p < 0.001).
Obstetrical histories are summarized in [Table 3]. Women in the low predicted success group were less likely to have had a prior vaginal
delivery (3.2%) compared with women in the moderate and high predicted success groups
(23.1 and 92.6%, respectively; p < 0.001). Women in the low predicted success group were also less likely to have
had a prior VBAC (0% vs. 6.6% vs. 68.1%; p < 0.001).
Intrapartum variables are summarized in [Table 4]. Induced labor occurred more frequently in the low predicted success group (53.7%)
compared with the moderate (15.2%) and high (6.0%) predicted success groups (p < 0.001). Correspondingly, patients with a low predicted success were less likely
to have spontaneous labor (46.3%) compared with patients with a moderate (84.8%) or
high (94.0%) predicted success (p < 0.001). Furthermore, patients with a low predicted success were more likely to
receive epidural anesthesia (88.4%) than those with a moderate (83.9%) or high (63.0%)
predicted success (p < 0.001).
Comorbidities are summarized in [Table 4]. There were no statistically significant differences in the rates of diabetes or
chronic hypertension among the three groups. In contrast, the rates of hypertensive
diseases of pregnancy (i.e., gestational hypertension and preeclampsia) showed significant
difference, with the low predicted success group exhibiting a higher rate of hypertensive
disease (23.2%) than the moderate (7.8%) and high (1.9%) predicted success groups
(p < 0.001). The low predicted success group also had a higher rate of intrapartum magnesium
use (10.5%) than the moderate (5.1%) and high (1.4%) predicted success groups (p < 0.002).
Perinatal outcomes are summarized in [Table 5]. The only statistically significant difference in outcomes was the rate of chorioamnionitis,
which trended slightly higher in patients with a lower predicted success (14.7%) or
moderate predicted success (14.1%) compared with a high (5.1%) predicted success (p = 0.003).
Discussion
The most significant finding of our study was that the application of the MFMU prediction
model did not predict TOLAC success in our exclusively Latina patient population.
The 567 Latinas who attempted TOLAC in our study achieved an overall 4-year VBAC rate
of 84.0%, which exceeds the national VBAC rate of 60 to 80%.[1] When we recalculated each patient's predicted VBAC success rate using non-Latina
ethnicity with all other variables unchanged, 141 patients (i.e., 24.9% of the study
population) who had previously fallen in the low or moderate predicted success groups
were now reclassified in the high-predicted success group ([Table 6]).
Table 6
Vaginal birth after cesarean rates compared among the three predicted success groups
based on patient's actual ethnicity versus hypothetical non-Latina ethnicity
|
Low predicted success
(<35%)
|
Moderate predicted success
(35–65%)
|
High predicted success
(>65%)
|
Total
|
p-Value
|
|
VBAC in Latinas
|
n = 62/95
|
65.26%
|
n = 216/256
|
84.38%
|
n = 198/216
|
91.67%
|
n = 476/567
|
84.04%
|
<0.001
|
|
VBAC in hypothetical non-Latina counterparts
|
n = 15/25
|
60.00%
|
n = 122/162
|
75.30%
|
n = 339/380
|
89.21%
|
n = 476/567
|
84.04%
|
<0.001
|
Abbreviation: VBAC, vaginal birth after cesarean.
The predicted VBAC success rates for the hypothetical non-Latina counterparts of our
study population in [Table 6] still underestimated actual VBAC outcomes, but to a lesser extent. Although Latina
ethnicity may not have been the sole reason for the discrepancy between predicted
and actual VBAC success rates, our results still raise important questions about whether
Latina ethnicity has any relevance to a patient's likelihood of TOLAC success, and
whether Latina ethnicity should continue to be treated as a negative predictive factor.
Past research that found an association between Latina ethnicity and TOLAC failure
did not elucidate an underlying physiologic or biologic explanation for this association.
Several studies including ours have demonstrated that obesity is a risk factor for
failed TOLAC,[9]
[10]
[11]
[12] and the prevalence of obesity in the United States is higher among Hispanics (47%)
than non-Hispanic whites (37.9%).[13] However, Latina ethnicity was determined to be a negative predictive factor independent
of obesity in the original MFMU prediction model (i.e., Latina ethnicity and obesity
were separate variables in the regression analysis). Therefore, obesity does not adequately
explain why Latina ethnicity has emerged as a risk factor for failed TOLAC in prior
studies. In fact, our Latina patients achieved a surprisingly high VBAC rate of 84.0%
despite having an average BMI of 33.7 kg/m2, compared with the average BMI of 26.4 kg/m2 in the MFMU cohort.
The primary limitation of our study was the use of self-reported information to determine
each patient's ethnicity for calculating TOLAC success. As in other studies on the
application of the MFMU prediction model, including the original study, no information
was provided in terms of how ethnicity or race was defined or determined. The “Latinas”
who served as the focus of our study represented a heterogeneous, poorly defined ethnic
group. We did not have information regarding maternal birthplace, which could have
helped us to compare the TOLAC success rates of Latinas born in the United Statesversus
Latinas born in Mexico versus Latinas born in other countries. The Latina population
in Southern California is predominantly of Mexican ancestry, and caution should be
exercised in applying generalizations from our study to Latinas of Puerto Rican, Cuban,
Central American, South American, or other origin. This underscores the limitations
and hazards of including race or ethnicity alone as a loosely defined variable.
Another limitation is that the number of patients who initially considered TOLAC but
ultimately decided to undergo elective repeat cesarean delivery is unknown, as is
the case in most studies on predicting TOLAC success. There are many reasons why a
patient may choose to decline TOLAC, including the obstetrician's counseling (whether
biased or unbiased), the patient's predicted success according the MFMU prediction
model, and the patient's own personal values, preferences, and motivations. Our results
may have differed if these patients had chosen to undergo TOLAC and were included
in our study.
Our study also did not include information regarding the duration of labor for each
patient undergoing TOLAC; therefore, it is unknown whether specific clinical interventions
or management practices contributed to our success rates. The national changes in
practice patterns that have developed since the original MFMU study in 2007 could
possibly explain the higher than expected VBAC rates in our study. For example, the
2014 Obstetric Care Consensus on “Safe Prevention of the Primary Cesarean Delivery”
currently allows women with a cervical dilation of at least 6 cm to continue labor
for 4 hours with ruptured membranes and adequate uterine activity, or 6 hours with
inadequate uterine activity.[14] Management of category II fetal heart rate tracings were also not as standardized
prior to the algorithm published by Clark et al in 2013.[15]
Regardless of the limitations, our study has ultimately demonstrated that Latinas
should not be discouraged from undergoing TOLAC solely based on a single variable
within the MFMU prediction model or based on a low predicted success score. As with
patients of any other ethnicity, a Latina patient's choice to undergo TOLAC versus
elective repeat cesarean delivery should involve a comprehensive shared decision-making
process that includes careful consideration of multiple factors.
