Are prediction models for vaginal birth after cesarean accurate?

VBAC calculator 2.0: Recent evidence

Following criticism for the use of race as a biological predictor of vaginal birth after cesarean (VBAC), an updated version of the Society for Maternal-Fetal Medicine (SMFM) VBAC calculator has been published. The variable "African American" or "Hispanic" (yes/no), which produced systematically lower chances of VBAC for nonwhites has been replaced with "chronic hypertension requiring treatment" (yes/no). Although there are no published external validation studies to date, developers report accuracy (area under the curve and calibration) nearly identical to the original calculator and it is published online for immediate use. This review examines the history of the calculator, measures of its validity, and recent studies measuring its performance among Hispanics, Blacks, Asians, and others with lower range scores. Underprediction of successful VBAC is evident in the original calculator, especially as predicted VBAC decreases. These studies raise a concern about the use of calculator scores in clinical management, that is, discouraging or restricting access to labor after cesarean (LAC) for parents with lower calculator scores. This raises special concern for minority populations who experience increased cesarean-related morbidity, face obstacles accessing LAC care, and who may benefit disproportionately from increased LAC uptake. Although calculator developers have discouraged using calculator scores to restrict access to LAC, such uses are documented. It is not clear what effect the removal of race will have on calculator performance, and further study is required before calculator scores are used in counseling. This includes studies that include large numbers of low scoring and minority patients.

Trial of labor after two cesarean sections: A retrospective case-control study

AIM

The objective of this study was to compare neonatal and maternal outcomes among women with two previous cesarean deliveries who undergo trial of labor after two cesarean section (TOLA2C) versus elective repeat cesarean delivery (ERCD). Our primary outcome was neonatal intensive care unit (NICU) admission. Secondary outcomes included APGAR score <7 at 5 min, TOLA2C success rate, uterine rupture, postpartum hemorrhage, maternal blood transfusion, maternal bowel and bladder injury, immediate postpartum infection, and maternal mortality.

METHODS

This retrospective cohort study was undertaken at a community medical center from January 1, 2008 to December 31, 2018. Inclusion criteria were women with a vertex singleton gestation at term and a history of two prior cesarean sections. Exclusion criteria included a previous successful TOLA2C, prior classical uterine incision or abdominal myomectomy, placenta previa or invasive placentation, multiple gestation, nonvertex presentation, history of uterine rupture or known fetal anomaly. Maternal and neonatal outcomes were assessed using Fisher exact test and Wilcoxon rank sum test.

RESULTS

A total of 793 patients fulfilled study criteria. There were no differences in neonatal intensive care unit admissions or 5-min APGAR scores <7 between the two groups. Sixty-eight percent of women who underwent TOLAC (N = 82) had a successful vaginal delivery. The uterine rupture rate was 1.16% (N = 1) in the TOLA2C group with no case of uterine rupture in the ERCD group. No difference in maternal morbidity was noted between the two groups. No maternal or neonatal mortalities occurred in either group.

CONCLUSIONS

There was no difference in maternal or neonatal morbidity among patients in our study population with two previous cesarean sections who opted for TOLA2C versus ERCD.

Development and Validation of a Model for Predicting Surgical Site Infection After Pelvic Organ Prolapse Surgery

IMPORTANCE

Surgical site infection (SSI) is a common and costly complication. Targeted interventions in high-risk patients may lead to a reduction in SSI; at present, there is no method to consistently identify patients at increased risk of SSI.

OBJECTIVE

The aim of this study was to develop and validate a model for predicting risk of SSI after pelvic organ prolapse surgery.

STUDY DESIGN

Women undergoing surgery between 2011 and 2017 were identified using Current Procedural Terminology codes from the Centers for Medicare and Medicaid Services 5% Limited Data Set. Surgical site infection ≤90 days of surgery was the primary outcome, with 41 candidate predictors identified, including demographics, comorbidities, and perioperative variables. Generalized linear regression was used to fit a full specified model, including all predictors and a reduced penalized model approximating the full model. Model performance was measured using the c-statistic, Brier score, and calibration curves. Accuracy measures were internally validated using bootstrapping to correct for bias and overfitting. Decision curves were used to determine the net benefit of using the model.

RESULTS

Of 12,334 women, 4.7% experienced SSI. The approximated model included 10 predictors. Model accuracy was acceptable (bias-corrected c-statistic [95% confidence interval], 0.603 [0.578-0.624]; Brier score, 0.045). The model was moderately calibrated when predicting up to 5-6 times the average risk of SSI between 0 and 25-30%. There was a net benefit for clinical use when risk thresholds for intervention were between 3% and 12%.

CONCLUSIONS

This model provides estimates of probability of SSI within 90 days after pelvic organ prolapse surgery and demonstrates net benefit when considering prevention strategies to reduce SSI.

Outcomes and risk factors for failed trial of labor after cesarean delivery (TOLAC) in women with one previous cesarean section: a Chinese population-based study

Objective

To evaluate the outcomes and risk factors for trial of labor after cesarean delivery (TOLAC) failure in patients in China.

Methods

Consecutive patients who had a previous cesarean delivery (CD) and attempted TOLAC were included from 2014 to 2020. Patients who successfully delivered were classified into the TOLAC success group. Patients who attempted TOLAC but had a repeat CD due to medical issues were classified into the TOLAC failure group. Multiple logistic regression analyses were performed to examine the risk factors for TOLAC failure.

Results

In total, 720 women who had a previous CD and attempted TOLAC were identified and included. The success rate of TOLAC was 84.2%(606/720). Seven patients were diagnosed with uterine rupture, none of whom underwent hysterectomy. Multiple logistic regression analysis showed that the induction of labor (OR = 2.843, 95% CI: 1.571–5.145, P < 0.001) was positively associated with TOLAC failure, but the thickness of the lower uterine segment (LUS) (OR = 0.215, 95% CI: 0.103–0.448, P < 0.001) was negatively associated with TOLAC failure.

Conclusions

This study suggested that TOLAC was effective in decreasing CD rates in the Chinese population. The induction of labor was positively associated with TOLAC failure, but the thickness of the LUS was negatively associated with TOLAC failure. Our findings need to be confirmed in larger samples with patients of different ethnicities.

Simplifying the prediction of vaginal birth after cesarean delivery: role of the cervical exam

OBJECTIVE

Predicting likelihood of vaginal birth after cesarean (VBAC) is a cornerstone in counseling patients considering a trial of labor after cesarean (TOLAC). Yet, the simplified Bishop score (SBS), a score comprised cervical dilation, station, and effacement assessment used to predict successful vaginal delivery, has not been applied to the TOLAC population. We evaluated the relationship between admission SBS and likelihood of successful VBAC. We also determined the predictive characteristics of SBS, compared to cervical dilation alone, for successful VBAC.

METHODS

This is a secondary analysis of a prospective cohort study of patients with a singleton gestation, ≥37 0/7 weeks gestation, and prior cesarean admitted to Labor & Delivery between 2010 and 2014. The primary outcome of successful VBAC was compared between those with a favorable (score >5) and unfavorable (score ≤5) admission SBS. Secondary outcomes were select maternal and neonatal outcomes. Adjusted risk ratios were estimated using multivariable logistic regression analyses. Receiver-operating characteristic curves compared predictive capabilities of cervical dilation alone to SBS for successful VBAC.

RESULTS

Of the 656 patients who underwent a TOLAC during the study period, 421 (64%) had a successful VBAC. 203 (31%) and 453 (69%) had a favorable and an unfavorable admission SBS, respectively. After adjusting for body mass index and prior vaginal delivery, patients with a favorable admission SBS had a 30% greater likelihood of successful VBAC compared to those with an unfavorable SBS (aRR 1.30, 95% CI 1.16-1.40). Admission cervical dilation alone performed similarly to SBS as a predictor of successful VBAC, with a receiver-operator characteristic curve area under the curve (AUC) of 0.68 (95% CI 0.64-0.72) versus an AUC 0.66 (95% CI 0.62-0.70), respectively (p = .07). There were no differences in adverse maternal or neonatal outcomes between those with an unfavorable and favorable SBS.

CONCLUSIONS

A favorable admission SBS is associated with an increased likelihood of VBAC. Although both admission SBS and cervical dilation alone are only modest predictors of VBAC, admission cervical dilation performs overall similarly to current models for VBAC prediction and is an objective, reproducible, and generalizable measure. Our study highlights the value of waiting until end of pregnancy (rather than the first prenatal visit) to conclude patient counseling on the decision to TOLAC in order to consider admission cervical assessment, particularly cervical dilation.

Vaginal birth after cesarean in women with no prior vaginal delivery carrying a large for gestational age baby

BACKGROUND

To study the factors associated with successful labor after cesarean (LAC) among women with no prior vaginal delivery, delivering a large for gestational age (LGA) baby.

METHODS

A retrospective case-control study at two tertiary medical centers in Israel, including all women undergoing LAC with no prior vaginal delivery during 2010-2020, delivering a singleton LGA newborn. Factors associated with successful vaginal delivery were examined by a multivariable analysis.

RESULTS

Overall, 323/505 (64.0%) had a successful LAC. Arrest of labor as the indication for previous CD was less common in the LAC success group [39 (12.1%) vs. 58 (31.9%), P < .001]. The rate of epidural analgesia was higher in the LAC success group [249 (77.1%) vs. 122 (67.0%), P = .014]. The rate of weight centile ≥97th was lower in the LAC success group [64 (19.8%) vs. 51 (28.0%), P = .035], as well as the rate of higher LAC birthweight than previous cesarean birthweight [264 (81.7%) vs. 162 (89.0%), P = .030]. In a multivariable logistic regression analysis, maternal height (aOR [95% CI]:1.09 (1.01, 1.17), P = .014) and epidural anesthesia (aOR [95% CI]:3.68 (1.31, 10.32), P = .013) were the only independent factors associated with LAC success.

CONCLUSIONS

Among primiparous women undergoing LAC carrying LGA newborns, the vaginal delivery rate is acceptable; however, uterine rupture risk is increased. Epidural administration is a modifiable factor and should be taken into consideration during LAC management.

Predictors of successful vaginal birth after cesarean without an epidural among women with no prior vaginal delivery

BACKGROUND

Data are scarce on predictors for success of labor after cesarean (LAC) among women delivering without epidural anesthesia (EA). We aimed to study the predictors for success of LAC among women with no prior vaginal delivery that did not use EA.

METHODS

A retrospective study including all women undergoing LAC between 3/2011 and 1/2021 with no prior vaginal delivery that did not use EA. Factors associated with successful vaginal birth after cesarean were examined using multivariable analysis.

RESULTS

Of the 466 no EA LAC, 339 (72.7%) delivered vaginally. Women in the successful LAC group had lower pregestational and predelivery BMI as compared to those who had a repeat cesarean [odds ratio (OR) 95% confidence interval (CI) 0.90 (0.85-0.94), P < 0.001, and 0.89 (0.85-0.93), P < 0.001, respectively]. The rate of labor dystocia in previous cesarean was lower in the LAC success group [92 (27.1%) vs 50 (39.4%), OR 95% CI 0.57 (0.37-0.88)]. Mean gestational age at LAC was lower in the LAC success group (38^5/7  ± 2^5/7 vs 39^5/7  ± 1^5/7 , P = 0.014). In a multivariable logistic regression analysis, the following factors were negatively and independently associated with LAC success: higher predelivery BMI [adjusted odds ratio (aOR) 95% CI 0.90 (0.86-0.95)], higher gestational age at previous cesarean and at LAC [aOR 95% CI 0.81 (0.70-0.93) and 0.97 (0.94-0.98), respectively], induction of labor [aOR 95% CI 0.08 (0.03-0.25)], and duration of ruptured membranes [aOR 95% CI 0.97 (0.96-0.99)].

CONCLUSIONS

We have identified that lower BMI, lower gestational age, shorter ruptured membranes duration, and spontaneous labor are associated with successful LAC among nonusers of EA with no prior vaginal delivery at one tertiary care facility in Israel.

Trial of labor after cesarean in primiparous women with fetal macrosomia

KEY MESSAGE

Spontaneous labor onset, epidural anesthesia and prior cesarean for non-arrest disorders are strong predictors of successful vaginal birth after cesarean in women delivering a macrosomic fetus.

PURPOSE

Lower rates of successful vaginal birth after cesarean in association with increasing birthweight were previously reported. We aimed to determine the factors associated with successful trial of labor after cesarean (TOLAC) among primiparous women with fetal macrosomia.

METHODS

A retrospective cohort study conducted during 2005-2019 at two university hospitals, including all primiparous women delivering a singleton fetus weighing ≥ 4000 g, after cesarean delivery at their first delivery. A multivariate analysis was performed to evaluate the characteristics associated with TOLAC success (primary outcome).

RESULTS

Of 551 primiparous women who met the inclusion criteria, 50.1% (n = 276) attempted a TOLAC and 174 (63.0%) successfully delivered vaginally. In a multivariate analysis, spontaneous onset of labor (aOR [95% CI] 3.68 (2.05, 6.61), P < 0.001), epidural anesthesia (aOR [95% CI] 2.38 (1.35, 4.20), P = 0.003) and history of cesarean delivery due to non-arrest disorder (aOR [95% CI] 2.25 (1.32, 3.85), P = 0.003) were the only independent factors associated with TOLAC success. Successful TOLAC was achieved in 82.0% (82/100) in the presence of all three favorable factors, 61.3% (65/106) in the presence of two factors and 38.6% (27/70) in the presence of one or less of these three factors (P < 0.001).

CONCLUSION

Spontaneous onset of labor, epidural anesthesia and prior cesarean delivery due to non-arrest disorders were independently associated with higher vaginal birth after cesarean rate among women with fetal macrosomia, with an overall favorable success rate in the presence of these factors. These findings should be implemented in patient counseling in those contemplating a vaginal birth in this setting.

Guided training has a beneficial effect on umbilical cord blood sampling quality

OBJECTIVE

Umbilical cord arterial blood gas analysis is important for neonatal assessment at birth, particularly for determining asphyxia. In April 2019, our labor ward faculty held systemic teaching sessions for midwives, aimed to describe and to exercise proper sampling from both the umbilical cord artery and vein, to ensure biological validity of the values obtained. Our aim was to estimate the rates of inadequate umbilical blood sampling and to evaluate the effect of guided training on the quality of sampling.

STUDY DESIGN

This retrospective interventional cohort study included all the women admitted to the delivery room, with a record of postpartum umbilical cord blood sampling. Umbilical cord sampling was considered adequate if two measurements were recorded with a veno-arterial pH gradient of at least 0.02 and an arterio-venous pCO₂ gradient of no less than 0.5 kPa. Rates of inadequate sampling were compared between women who gave birth in the year preceding and the year following the guidance. Clinical characteristics were compared between the groups of adequate and inadequate sampling.

RESULTS

Overall, 3,779 women gave birth in the year preceding guidance, and 3,649 in the subsequent year. Of these, 1,112 (29.4%) and 1,105 (30.2%), respectively, underwent umbilical sampling. In the year following the guidance, 750 (67.8%) adequate samples were drawn compared to 692 (62.2%) prior the guidance. This difference demonstrated significant improvement (OR 1.28, 95% CI 1.07-1.52, P = 0.006) in umbilical vessel sampling. Following multivariate logistic regression, inadequate sampling was associated with newborn weight below 2500 g (aOR 1.6, 95% CI 1.2-2.1, p = 0.001), spontaneous vaginal delivery with a possible fetal metabolic abnormality (aOR 2.2, 95% CI 1.7-2.7, p < 0.001), and vacuum deliveries (aOR 1.9, 95% CI 1.5-2.5, p < 0.001).

CONCLUSIONS

Guided training of proper umbilical blood sampling may reduce the rate of inadequate postpartum blood gas results. Labor wards should consider carrying out annual demonstrations of proper umbilical blood collection, with emphasis on factors that affect the quality of the samplings.

Risk management of vaginal birth after cesarean section (Review)

The increasing number of patients who desire to experience vaginal birth after cesarean (VBAC) and the optimized protocols for trial of labor after cesarean (TOLAC) has led to a shift of old obstetrical paradigms. The VBAC trend is accompanied with numerous challenges for healthcare professionals, from establishing suitability of each pregnant patient profile for TOLAC to active labor management, and ethical or legal issues, which occasionally are not included in specific guidelines. That is why an individualized risk assessment and management can serve obstetricians as a useful tool for improving outcomes of patients, satisfaction, and also for avoiding legal or moral liabilities. The risk management concept aims to reduce foreseen risks and to emulate strategies for prediction and prevention of unwanted events. In obstetrics, and particularly for the VBAC topic, this concept is relatively new and undefined, and thus its features are disparate between guideline recommendations and clinical studies. This narrative review intends to offer a new and organic perspective over clinical aspects of TOLAC and VBAC risk management.

Obstetric iatrogenesis in the United States: the spectrum of unintentional harm, disrespect, violence, and abuse

'Medical iatrogenesis' was first defined by Illich as injuries 'done to patients by ineffective, unsafe, and erroneous treatments'. Following Lokumage's original usage of the term, this paper explores 'obstetric iatrogenesis' along a spectrum ranging from unintentional harm (UH) to overt disrespect, violence, and abuse (DVA), employing the acronym 'UHDVA' for this spectrum. This paper draws attention to the systemic maltreatment rooted in the technocratic model of birth, which includes UH normalized forms of mistreatment that childbearers and providers may not recognize as abusive. Equally, this paper assesses how obstetric iatrogenesis disproportionately impacts Black, Indigenous, and People of Color (BIPOC), contributing to worse perinatal outcomes for BIPOC childbearers. Much of the work on 'obstetric violence' that documents the most detrimental end of the UHDVA spectrum has focused on low-to-middle income countries in Latin America and the Caribbean. Based on a dataset of 62 interviews and on our personal observations, this paper shows that significant UHDVA also occurs in the high-income U.S., provide concrete examples, and suggest humanistic solutions.

Prediction of fetal weight based on back propagation neural network optimized by genetic algorithm

Fetal weight is an important index to judge fetal development and ensure the safety of pregnant women. However, fetal weight cannot be directly measured. This study proposed a prediction model of fetal weight based on genetic algorithm to optimize back propagation (GA-BP) neural network. Using random number table method, 80 cases of pregnant women in our hospital from September 2018 to March 2019 were divided into control group and observation group, 40 cases in each group. The doctors in the control group predicted the fetal weight subjectively according to routine ultrasound and physical examination. In the observation group, the continuous weight change model of pregnant women was established by using the regression model and the historical physical examination data obtained by feature normalization pretreatment, and then the genetic algorithm (GA) was used to optimize the initial weights and thresholds of back propagation (BP) neural network to establish the fetal weight prediction model. The coincidence rate of fetal weight was compared between the two groups after birth. Results: The prediction error of GA-BPNN was controlled within 6%. And the accuracy of GA-BPNN was 76.3%, which were 14.5% higher than that of traditional methods. According to the error curve, GA-BP is more effective in predicting the actual fetal weight. Conclusion: The GA-BPNN model can accurately and quickly predict fetal weight.

Fetal Head Station at Second-Stage Dystocia and Subsequent Trial of Labor After Cesarean Delivery Success Rate

OBJECTIVE

To investigate whether fetal head station at the index cesarean delivery is associated with a subsequent trial of labor success rate among primiparous women.

METHODS

A retrospective cohort study conducted at two tertiary medical centers included all primiparous women with subsequent delivery after cesarean delivery for second-stage dystocia during 2009-2019, identified from the electronic medical record databases. Univariate and multivariate analyses were performed to assess the factors associated with successful trial of labor after cesarean (TOLAC) (primary outcome). Additionally, all women with failed TOLAC were matched one-to-one to women with successful TOLAC, according to factors identified in the univariate analysis.

RESULTS

Of 481 primiparous women with prior cesarean delivery for second-stage dystocia, 64.4% (n=310) attempted TOLAC, and 222 (71.6%) successfully delivered vaginally. The rate of successful TOLAC was significantly higher in those with fetal head station below the ischial spines at the index cesarean delivery, as compared with those with higher head station (79.0% vs 60.5%, odds ratio [OR] 2.46, 95% CI 1.49-4.08). The proportion of neonates weighing more than 3,500 g in the subsequent delivery was lower in those with successful TOLAC compared with failed TOLAC (29.7% vs 43.2%, OR 0.56, 95% CI 0.33-0.93). In a multivariable analysis, lower fetal head station at the index cesarean delivery was the only independent factor associated with TOLAC success (adjusted OR 2.38, 95% CI 1.43-3.96). Matching all women with failed TOLAC one-to-one to women with successful TOLAC, according to birth weight and second-stage duration at the subsequent delivery, lower fetal head station at the index cesarean delivery remained the only factor associated with successful TOLAC.

CONCLUSION

Lower fetal head station at the index cesarean delivery for second-stage dystocia was independently associated with a higher vaginal birth after cesarean rate, with an overall acceptable success rate. These findings should improve patient counseling and reassure those who wish to deliver vaginally after prior second-stage arrest.

Development and Validation of Predictive Models for Vaginal Birth After Cesarean Delivery in China

Background

The rate of delivery by cesarean section is rising in China, where vaginal birth after cesarean (VBAC) is in its early stages. There are no validated screening tools to predict VBAC success in China. The objective of this study was to identify the variables predicting the likelihood of successful VBAC to create a predictive model.

Material/Methods

This multicenter, retrospective study included 1013 women at ≥28 gestational weeks with a vertex singleton gestation and 1 prior low-transverse cesarean from January 2017 to December 2017 in 11 public tertiary hospitals within 7 provinces of China. Two multivariable logistic regression models were developed: (1) at a first-trimester visit and (2) at the pre-labor admission to hospital. The models were evaluated with the area under the receiver operating characteristic curve (AUC) and internally validated using k-fold cross-validation. The pre-labor model was calibrated and a graphic nomogram and clinical impact curve were created.

Results

A total of 87.3% (884/1013) of women had successful VBAC, and 12.7% (129/1013) underwent unplanned cesarean delivery after a failed trial of labor. The AUC of the first-trimester model was 0.661 (95% confidence interval [CI]: 0.61–0.712), which increased to 0.758 (95% CI: 0.715–0.801) in the pre-labor model. The pre-labor model showed good internal validity, with AUC 0.743 (95% CI: 0.694–0.785), and was well calibrated.

Conclusions

VBAC provides women the chance to experience a vaginal delivery. Using a pre-labor model to predict successful VBAC is feasible and may help choose mode of birth and contribute to a reduction in cesarean delivery rate.

Vaginal birth after cesarean in women with pre-labor rupture of membranes at term

INTRODUCTION

Women with a successful vaginal birth after cesarean delivery (VBAC) have less morbidity than women undergoing repeat cesarean delivery. Although several scores and models predict VBAC success, none focus on pregnant women with pre-labor rupture of membranes (PROM). We evaluated different clinical variables that might predict the likelihood of VBAC success in women with PROM.

STUDY DESIGN

A retrospective, 5-year study in a large referral center from December 2013 to December 2018. Inclusion criteria were women with singleton pregnancy, at or beyond 37 weeks' gestation, admitted with spontaneous PROM, with one previous cesarean delivery that consented trial of labor. Exclusion criteria were history of two cesarean deliveries, multiple gestations or obstetrical contraindications for TOLAC, including maternal request for repeat cesarean delivery. Variables associated with successful VBA C were identified using multivariate logistic regression.

RESULTS

Of 302 women in the cohort, 74.8% (226/302) delivered vaginally (successful VBAC) and 25.2% (76/302) by repeat CD (failed TOLAC). Multiple logistic regression showed that duration of PROM-to-delivery time was the only significant factor associated with successful TOLAC (78% delivered vaginally within 24 h and 93.3% within 36 h), while none of the other variables (maternal age, gravidity, BMI, gestational and birthweight at delivery, effacement or station at admission, previous indication for cesarean delivery, time interval between previous and current delivery, presence of meconium-stained liquor, and documented temperature >38 °C) were associated with the prediction of successful VBAC.

CONCLUSION

Women with spontaneous pre-labor PROM and previous cesarean delivery have high success rates of VBAC. The only significant variable associated with successful TOLAC in women with spontaneous PROM at term was the duration of PROM-to-delivery time. Our findings suggest that the success rate of VBAC is likely multifactorial, not-necessarily related to a specific underlying factor, and in the absence of contraindications, a fair trial of labor after cesarean delivery is justified.

Prediction of vaginal birth after cesarean delivery in Southeast China: a retrospective cohort study

BACKGROUND

We aimed to develop and validate a nomogram for effective prediction of vaginal birth after cesarean (VBAC) and guide future clinical application.

METHODS

We retrospectively analyzed data from hospitalized pregnant women who underwent trial of labor after cesarean (TOLAC), at the Fujian Provincial Maternity and Children's Hospital, between October 2015 and October 2017. Briefly, we included singleton pregnant women, at a gestational age above 37 weeks who underwent a primary cesarean section, in the study. We then extracted their sociodemographic data and clinical characteristics, and randomly divided the samples into training and validation sets. We employed the least absolute shrinkage and selection operator (LASSO) regression to select variables and construct VBAC success rate in the training set. Thereafter, we validated the nomogram using the concordance index (C-index), decision curve analysis (DCA), and calibration curves. Finally, we adopted the Grobman's model to perform comparisons with published VBAC prediction models.

RESULTS

Among the 708 pregnant women included according to inclusion criteria, 586 (82.77%) patients were successfully for VBAC. Multivariate logistic regression models revealed that maternal height (OR, 1.11; 95% CI, 1.04 to 1.19), maternal BMI at delivery (OR, 0.89; 95% CI, 0.79 to 1.00), fundal height (OR, 0.71; 95% CI, 0.58 to 0.88), cervix Bishop score (OR, 3.27; 95% CI, 2.49 to 4.45), maternal age at delivery (OR, 0.90; 95% CI, 0.82 to 0.98), gestational age (OR, 0.33; 95% CI, 0.17 to 0.62) and history of vaginal delivery (OR, 2.92; 95% CI, 1.42 to 6.48) were independently associated with successful VBAC. The constructed predictive model showed better discrimination than that from the Grobman's model in the validation series (c-index 0.906 VS 0.694, respectively). On the other hand, decision curve analysis revealed that the new model had better clinical net benefits than the Grobman's model.

CONCLUSIONS

VBAC will aid in reducing the rate of cesarean sections in China. In clinical practice, the TOLAC prediction model will help improve VBAC's success rate, owing to its contribution to reducing secondary cesarean section.

Can assessing the angle of progression before labor onset assist to predict vaginal birth after cesarean?: A prospective cohort observational study

Objective: To assess whether pre-labor measurement of the angle of progression (AOP) can assist in predicting a successful vaginal birth after cesarean in women without a previous vaginal birth.Methods: A prospective observational cohort study performed in a single tertiary center including women at term with a single previous cesarean delivery (CD), without prior vaginal births, who desire a trial of labor. Transperineal ultrasound was used to measure the AOP before the onset of labor. The managing staff in the delivery suite was blinded to the ultrasound measurements. Clinical data and delivery outcome were retrieved from medical records. The study was approved by the institutional ethics committee (KMC 0117-10).Results: Of the 111 women included in the study, 67 (60.4%) had a successful vaginal birth after CD. Women were sonographically assessed at a median of 3 days [interquartile range (IQR) 1-3 days] prior to delivery. The median AOP was significantly narrower in women who eventually underwent a CD than in those who delivered vaginally (88°, IQR 78-96° vs. 99°, IQR 89-107°, respectively; p < .001). An AOP >98° (derived from a receiver operating characteristic curve) was associated with a successful vaginal birth after CD in 87.5% of women. Multivariable regression analysis demonstrated that each additional 1° in the AOP increases the chance for a successful vaginal birth after CD by 6%.Conclusions: Pre-labor AOP may be a useful sonographic tool for predicting vaginal birth after CD and can assist in consulting primiparous women with a prior CD opting for a trial of labor.

Prediction of vaginal birth after cesarean deliveries using machine learning

BACKGROUND

Efforts to reduce cesarean delivery rates to 12-15% have been undertaken worldwide. Special focus has been directed towards parturients who undergo a trial of labor after cesarean delivery to reduce the burden of repeated cesarean deliveries. Complication rates are lowest when a vaginal birth is achieved and highest when an unplanned cesarean delivery is performed, which emphasizes the need to assess, in advance, the likelihood of a successful vaginal birth after cesarean delivery. Vaginal birth after cesarean delivery calculators have been developed in different populations; however, some limitations to their implementation into clinical practice have been described. Machine-learning methods enable investigation of large-scale datasets with input combinations that traditional statistical analysis tools have difficulty processing.

OBJECTIVE

The aim of this study was to evaluate the feasibility of using machine-learning methods to predict a successful vaginal birth after cesarean delivery.

STUDY DESIGN

The electronic medical records of singleton, term labors during a 12-year period in a tertiary referral center were analyzed. With the use of gradient boosting, models that incorporated multiple maternal and fetal features were created to predict successful vaginal birth in parturients who undergo a trial of labor after cesarean delivery. One model was created to provide a personalized risk score for vaginal birth after cesarean delivery with the use of features that are available as early as the first antenatal visit; a second model was created that reassesses this score after features are added that are available only in proximity to delivery.

RESULTS

A cohort of 9888 parturients with 1 previous cesarean delivery was identified, of which 75.6% of parturients (n=7473) attempted a trial of labor, with a success rate of 88%. A machine-learning-based model to predict when vaginal delivery would be successful was developed. When features that are available at the first antenatal visit are used, the model showed a receiver operating characteristic curve with area under the curve of 0.745 (95% confidence interval, 0.728-0.762) that increased to 0.793 (95% confidence interval, 0.778-0.808) when features that are available in proximity to the delivery process were added. Additionally, for the later model, a risk stratification tool was built to allocate parturients into low-, medium-, and high-risk groups for failed trial of labor after cesarean delivery. The low- and medium-risk groups (42.4% and 25.6% of parturients, respectively) showed a success rate of 97.3% and 90.9%, respectively. The high-risk group (32.1%) had a vaginal delivery success rate of 73.3%. Application of the model to a cohort of parturients who elected a repeat cesarean delivery (n=2145) demonstrated that 31% of these parturients would have been allocated to the low- and medium-risk groups had a trial of labor been attempted.

CONCLUSION

Trial of labor after cesarean delivery is safe for most parturients. Success rates are high, even in a population with high rates of trial of labor after cesarean delivery. Application of a machine-learning algorithm to assign a personalized risk score for a successful vaginal birth after cesarean delivery may help in decision-making and contribute to a reduction in cesarean delivery rates. Parturient allocation to risk groups may help delivery process management.

Maternal and neonatal outcome after vaginal breech delivery at term after cesarean section - a prospective cohort study of the Frankfurt breech at term cohort (FRABAT)

OBJECTIVE

To compare the neonatal and maternal outcomes as well as the mode of delivery of intended vaginal breech deliveries in women with a prior cesarean section to primiparous patients.

STUDY DESIGN

The prospective monocenter cohort study was conducted among 604 women who presented for an intended vaginal singleton breech delivery at term between January 2007 and December 2016.

RESULTS

Out of 37 women with a prior cesarean 19 had a successful vaginal delivery. 344 of 567 primiparous women had a successful vaginal delivery. Neonatal morbidity and mortality as well as maternal outcome were not significantly different in successful vaginal deliveries of women with prior cesarean compared to primiparous patients. The cesarean section rate was not significantly higher in the group of women with a prior cesarean (49%) compared to the group of primipara (39%).

CONCLUSION

A prior cesarean should not be taken as an exclusion criterion for a planned vaginal delivery out of a breech presentation at term. Large multicenter, case-controlled studies are necessary to implement international guidelines.

Can recurrent cesarean section due to arrest of descent be predicted by newborn weight difference?

OBJECTIVE

To evaluate if newborn weight difference is associated with the mode of delivery in women with a previous cesarean section due to arrest of descent.

STUDY DESIGN

This retrospective cohort analysis included all women admitted to the delivery room of Carmel Medical Center with a singleton fetus at vertex presentation and a prior cesarean section for arrest of descent. A comparison was made between women who had a subsequent successful vaginal birth after cesarean delivery vs. a repeat cesarean section for arrest of descent. The primary outcome was newborn weight difference between the previous cesarean section and the present delivery. Secondary outcomes were gestational age, gravidity, age, induction of labor, previous vaginal birth and epidural analgesia.

RESULTS

Of 179 women with a prior cesarean section due to arrest of descent, 55 women (30.7 %) underwent an elective repeat cesarean section. Of the remaining 124 women, 95 women (76.6 %) achieved a vaginal delivery. Out of the 29 cases who underwent a repeat cesarean section, 18 women had a cesarean section for arrest of descent. Women who achieved vaginal delivery were more likely to be with higher gravidity, a previous vaginal delivery and a lower rate of epidural anesthesia. Following multivariate logistic regression, the women who required a cesarean section due to arrest of descent, had significantly higher birth weight in the current than in the previous pregnancy, compared to women achieving vaginal delivery (Odds Ratio 4.7, CI 95 % 1.4-15.7, P = 0.012).

CONCLUSION

Current birth weight higher than the previous newborn weight in a cesarean section for arrest of descent is associated with lower likelihood of successful vaginal birth after cesarean delivery and therefore should be taken in consideration during fetal weight estimation and the decision on the mode of delivery. This issue should be explored in future prospective large-cohort studies.