Trial of labor after cesarean, vaginal birth after cesarean, and the risk of uterine rupture: an expert review.

The decision to pursue a trial of labor after cesarean delivery is complex and depends on patient preference, the likelihood of successful vaginal birth after cesarean delivery, assessment of the risks vs benefits of trial of labor after cesarean delivery, and available resources to support safe trial of labor after cesarean delivery at the planned birthing center. The most feared complication of trial of labor after cesarean delivery is uterine rupture, which can have catastrophic consequences, including substantial maternal and perinatal morbidity and mortality. Although the absolute risk of uterine rupture is low, several clinical, historical, obstetrical, and intrapartum factors have been associated with increased risk. It is therefore critical for clinicians managing patients during trial of labor after cesarean delivery to be aware of these risk factors to appropriately select candidates for trial of labor after cesarean delivery and maximize the safety and benefits while minimizing the risks. Caution is advised when considering labor augmentation and induction in patients with a previous cesarean delivery. With established hospital safety protocols that dictate close maternal and fetal monitoring, avoidance of prostaglandins, and careful titration of oxytocin infusion when induction agents are needed, spontaneous and induced trial of labor after cesarean delivery are safe and should be offered to most patients with 1 previous low transverse, low vertical, or unknown uterine incision after appropriate evaluation, counseling, planning, and shared decision-making. Future research should focus on clarifying true risk factors and identifying the optimal approach to intrapartum and induction management, tools for antenatal prediction, and strategies for prevention of uterine rupture during trial of labor after cesarean delivery. A better understanding will facilitate patient counseling, support efforts to improve trial of labor after cesarean delivery and vaginal birth after cesarean delivery rates, and reduce the morbidity and mortality associated with uterine rupture during trial of labor after cesarean delivery.

Induction of labor vs expectant management among low-risk patients with 1 prior cesarean delivery.

BACKGROUND: Studies that have compared induction of labor in individuals with 1 prior cesarean delivery to expectant management have shown conflicting results. OBJECTIVE: To determine the association between clinical outcomes and induction of labor at 39 weeks in a national sample of otherwise low-risk patients with 1 prior cesarean delivery. STUDY DESIGN: This cross-sectional study analyzed 2016 to 2021 US Vital Statistics birth certificate data. Individuals with vertex, singleton pregnancies, and 1 prior cesarean delivery were included. Patients with prior vaginal deliveries, delivery before 39 weeks 0 days or after 42 weeks 6 days of gestation, and medical comorbidities were excluded. The primary exposure of interest was induction of labor at 39 weeks 0 days to 39 weeks 6 days compared to expectant management with delivery from 40 weeks 0 days to 42 weeks 6 days. The primary outcome was vaginal delivery. The main secondary outcomes were separate maternal and neonatal morbidity composites. The maternal morbidity composite included uterine rupture, operative vaginal delivery, peripartum hysterectomy, intensive care unit admission, and transfusion. The neonatal morbidity composite included neonatal intensive care unit admission, Apgar score less than 5 at 5 minutes, immediate ventilation, prolonged ventilation, and seizure or serious neurological dysfunction. Unadjusted and adjusted log binomial regression models accounting for demographic variables and the exposure of interest (induction vs expectant management) were performed. Results are presented as unadjusted and adjusted risk ratios with 95% confidence intervals. RESULTS: From 2016 to 2021, a total of 198,797 individuals with vertex, singleton pregnancies, and 1 prior cesarean were included in the primary analysis. Of these individuals, 25,915 (13.0%) underwent induction of labor from 39 weeks 0 days to 39 weeks 6 days and 172,882 (87.0%) were expectantly managed with deliveries between 40 weeks 0 days and 42 weeks 6 days. In adjusted analyses, patients induced at 39 weeks were more likely to have a vaginal delivery when compared to those expectantly managed (38.0% vs 31.8%; adjusted risk ratio 1.32, 95% confidence interval 1.28, 1.36). Among those who had vaginal deliveries, induction of labor was associated with increased likelihood of operative vaginal delivery (11.1% vs 10.0; adjusted risk ratio 1.15, 95% confidence interval 1.07, 1.24). The maternal morbidity composite occurred in 0.9% of individuals in both the induction and expectant management groups (adjusted risk ratio 0.92, 95% confidence interval 0.79, 1.06). The rates of uterine rupture (0.3%), peripartum hysterectomy (0.04% vs 0.05%), and intensive care unit admission (0.1% vs 0.2%) were all relatively low and did not differ significantly between groups. There was also no significant difference in the neonatal morbidity composite between the induction and expectant management groups (7.3% vs 6.7%; adjusted risk ratio 1.04, 95% confidence interval 0.98, 1.09). CONCLUSION: When compared to expectant management, elective induction of labor at 39 weeks in low-risk patients with 1 prior cesarean delivery was associated with a significantly higher likelihood of vaginal delivery with no difference in composite maternal and neonatal morbidity outcomes. Prospective studies are needed to better elucidate the risks and benefits of induction of labor in this patient population.

The association between obesity and the success of trial of labor after cesarean delivery (TOLAC) in women with past vaginal delivery.

OBJECTIVES: To evaluate the effect of overweight (body mass index; BMI 25.0-29.9 kg/m2), and obesity (BMI>30 kg/m2), on the success of trial of labor after cesarean delivery (TOLAC), with consideration of successful past vaginal birth. METHODS: This retrospective cohort study was performed using electronic database of obstetrics department at a university-affiliated tertiary medical center. All women admitted for TOLAC at 37-42 weeks of gestational age, carrying a singleton live fetus at cephalic presentation, with a single previous low segment transverse cesarean delivery between 1/2015 and 5/2021 were included. Primary outcome was the rate of cesarean delivery during labor, and subgroup analysis was performed for the presence of past vaginal birth. RESULTS: Of the 1200 TOLAC deliveries meeting the inclusion criteria, 61.9 % had BMI in the normal range, 24.6 % were overweight (BMI 25.0-29.9 kg/m2), and 13.4 % were obese (BMI of 30 kg/m2 and over). Using a multivariate analysis, BMI≥30 kg/m2 was associated with increased risk of cesarean delivery compared to normal weight. However, in the subgroup of 292 women with a history of successful vaginal birth BMI did not affect TOLAC success. CONCLUSIONS: BMI does not affect the success of TOLAC in women with previous vaginal birth. This information should be considered during patients counselling, in order to achieve a better selection of mode of delivery and higher patients' satisfaction.

Midwifery care during labor and birth in the United States.

The intrapartum period is a crucial time in the continuum of pregnancy and parenting. Events during this time are shaped by individuals' unique sociocultural and health characteristics and by their healthcare providers, practice protocols, and the physical environment in which care is delivered. Childbearing people in the United States have less opportunity for midwifery care than in other high-income countries. In the United States, there are 4 midwives for every 1000 live births, whereas, in most other high-income countries, there are between 30 and 70 midwives. Furthermore, these countries have lower maternal and neonatal mortality rates and have consistently lower costs of care. National and international evidences consistently report that births attended by midwives have fewer interventions, cesarean deliveries, preterm births, inductions of labor, and more vaginal births after cesarean delivery. In addition, midwifery care is consistently associated with respectful care and high patient satisfaction. Midwife-physician collaboration exists along a continuum, including births attended independently by midwives, births managed in consultation with a physician, and births attended primarily by a physician with a midwife acting as consultant on the normal aspects of care. This expert review defined midwifery care and provided an overview of midwifery in the United States with an emphasis on the intrapartum setting. Health outcomes associated with midwifery care, specific models of intrapartum care, and workforce issues have been presented within national and international contexts. Recommendations that align with the integration of midwifery have been suggested to improve national outcomes and reduce pregnancy-related disparities.

Preferences of pregnant individuals to undergo labor after one cesarean in southern China.

BACKGROUND: Labor after cesarean (LAC) remains an optional delivery method among healthy pregnant individuals. Exploring women's attitudes, preferences, reasons for previous cesarean delivery, and the incentives underlying pregnant individuals' preferences could help us understand their choice of delivery mode. In this study we evaluated the preferences and attitudes of eligible pregnant women regarding participation in a LAC in Foshan, China. METHODS: A cross-sectional survey was conducted among 438 pregnant individuals with one prior cesarean delivery (CD) who attended their antenatal examination at a tertiary hospital in southern China, between November 1, 2018, and October 31, 2019. Information on demographic characteristics, obstetric data, preferences for LAC, and incentives for LAC were analyzed. RESULTS: Overall, 85.4% (374/438) of women preferred LAC if they did not have contraindications before delivery, whereas 12.3% (54/438) refused and 2.3% (10/438) were unsure. Participants reported that the most important factors affecting their willingness to undergo LAC were safety indicators (i.e., "ability of hospitals to perform emergency cesarean delivery" [score of 9.28 ± 1.86]), followed by accessibility indicators (i.e., "priority bed arrangements" [score of 9.17 ± 1.84]). Logistic regression analysis indicated that neonatal wellbeing with the prior CD was an independent influencing factor (OR = 2.235 [95%CI: 1.115-4.845], p = 0.024) affecting willingness to access LAC in the subsequent pregnancy. CONCLUSIONS: We found a high preference for LAC among pregnant individuals without contraindications before delivery in southern China. Healthcare providers need to ensure access to LAC and increase pregnant individuals' LAC willingness through high-quality shared decsision-making in alignment with patient preferences.

Prediction of vaginal birth after cesarean delivery in term gestations: a calculator without race and ethnicity.

BACKGROUND: Investigators have attempted to derive tools that could provide clinicians with an easily obtainable estimate of the chance of vaginal birth after cesarean delivery for those who undertake trial of labor after cesarean delivery. One tool that has been validated externally was derived from data from the Maternal-Fetal Medicine Units Cesarean Registry. However, concern has been raised that this tool includes the socially constructed variables of race and ethnicity. OBJECTIVE: This study aimed to develop an accurate tool to predict vaginal birth after cesarean delivery, using data easily obtainable early in pregnancy, without the inclusion of race and ethnicity. STUDY DESIGN: This was a secondary analysis of the Cesarean Registry of the Maternal-Fetal Medicine Units Network. The approach to the current analysis is similar to that of the analysis in which the previous vaginal birth after cesarean delivery prediction tool was derived. Specifically, individuals were included in this analysis if they were delivered on or after 37 0/7 weeks' gestation with a live singleton cephalic fetus at the time of labor and delivery admission, had a trial of labor after cesarean delivery, and had a history of 1 previous low-transverse cesarean delivery. Information was only considered for inclusion in the model if it was ascertainable at an initial prenatal visit. Model selection and internal validation were performed using a cross-validation procedure, with the dataset randomly and equally divided into a training set and a test set. The training set was used to identify factors associated with vaginal birth after cesarean delivery and build the logistic regression predictive model using stepwise backward elimination. A final model was generated that included all variables found to be significant (P<.05). The accuracy of the model to predict vaginal birth after cesarean delivery was assessed using the concordance index. The independent test set was used to estimate classification errors and validate the model that had been developed from the training set, and calibration was assessed. The final model was then applied to the overall analytical population. RESULTS: Of the 11,687 individuals who met the inclusion criteria for this secondary analysis, 8636 (74%) experienced vaginal birth after cesarean delivery. The backward elimination variable selection yielded a model from the training set that included maternal age, prepregnancy weight, height, indication for previous cesarean delivery, obstetrical history, and chronic hypertension. Vaginal birth after cesarean delivery was significantly more likely for women who were taller and had a previous vaginal birth, particularly if that vaginal birth had occurred after a previous cesarean delivery. Conversely, vaginal birth after cesarean delivery was significantly less likely for women whose age was older, whose weight was heavier, whose indication for previous cesarean delivery was arrest of dilation or descent, and who had a history of medication-treated chronic hypertension. The model had excellent calibration between predicted and empirical probabilities and, when applied to the overall analytical population, an area under the receiver operating characteristic curve of 0.75 (95% confidence interval, 0.74-0.77), which is similar to the area under the receiver operating characteristic curve of the previous model (0.75) that included race and ethnicity. CONCLUSION: We successfully derived an accurate model (available at https://mfmunetwork.bsc.gwu.edu/web/mfmunetwork/vaginal-birth-after-cesarean-calculator), which did not include race or ethnicity, for the estimation of the probability of vaginal birth after cesarean delivery.

Predicting obstetrical anal sphincter injuries in patients who undergo vaginal birth after cesarean delivery.

BACKGROUND: Women with a history of previous cesarean delivery must weigh the numerous potential risks and benefits of elective repeat cesarean delivery or trial of labor after cesarean delivery. Notably, 1 important risk of vaginal delivery is obstetrical anal sphincter injuries. Furthermore, the rate of obstetrical anal sphincter injuries is high among women undergoing vaginal birth after cesarean delivery. However, the risk of obstetrical anal sphincter injuries is not routinely included in the trial of labor after cesarean delivery counseling, and there is no tool available to risk stratify obstetrical anal sphincter injuries among women undergoing vaginal birth after cesarean delivery. OBJECTIVE: This study aimed to develop and validate a predictive model to estimate the risk of obstetrical anal sphincter injuries in the setting of vaginal birth after cesarean delivery population to improve antenatal counseling of patients regarding risks of trial of labor after cesarean delivery. STUDY DESIGN: This study was a secondary subgroup analysis of the Maternal-Fetal Medicine Units Network Trial of Labor After Cesarean Delivery prospective cohort (1999-2002). We identified women within the Maternal-Fetal Medicine Units Network cohort with 1 previous cesarean delivery followed by a term vaginal birth after cesarean delivery. This Maternal-Fetal Medicine Units Network Vaginal Birth After Cesarean Delivery cohort was stratified into 2 groups based on the presence of obstetrical anal sphincter injuries, and baseline characteristics were compared with bivariate analysis. Significant covariates in bivariate testing were included in a backward stepwise logistic regression model to identify independent risk factors for obstetrical anal sphincter injuries and generate a predictive model for obstetrical anal sphincter injuries in the setting of vaginal birth after cesarean delivery. Internal validation was performed using bootstrapped bias-corrected estimates of model concordance indices, Brier scores, Hosmer-Lemeshow chi-squared values, and calibration plots. External validation was performed using data from a single-site retrospective cohort of women with a singleton vaginal birth after cesarean delivery from January 2011 to December 2016. RESULTS: In this study, 10,697 women in the Maternal-Fetal Medicine Units Network Trial of Labor After Cesarean Delivery cohort met the inclusion criteria, and 669 women (6.3%) experienced obstetrical anal sphincter injuries. In the model, factors independently associated with obstetrical anal sphincter injuries included use of forceps (adjusted odds ratio, 5.08; 95% confidence interval, 4.10-6.31) and vacuum assistance (adjusted odds ratio, 2.64; 95% confidence interval, 2.02-3.44), along with increasing maternal age (adjusted odds ratio, 1.05; 95% confidence interval, 1.04-1.07 per year), body mass index (adjusted odds ratio, 0.99; 95% confidence interval, 0.97-1.00 per unit kg/m2), previous vaginal delivery (adjusted odds ratio, 0.19; 95% confidence interval, 0.15-0.23), and tobacco use during pregnancy (adjusted odds ratio, 0.59; 95% confidence interval, 0.43-0.82). Internal validation demonstrated appropriate discrimination (concordance index, 0.790; 95% confidence interval, 0.771-0.808) and calibration (Brier score, 0.047). External validation used data from 1266 women who delivered at a tertiary healthcare system, with appropriate model discrimination (concordance index, 0.791; 95% confidence interval, 0.735-0.846) and calibration (Brier score, 0.046). The model can be accessed at oasisriskscore.xyz. CONCLUSION: Our model provided a robust, validated estimate of the probability of obstetrical anal sphincter injuries during vaginal birth after cesarean delivery using known antenatal risk factors and 1 modifiable intrapartum risk factor and can be used to counsel patients regarding risks of trial of labor after cesarean delivery compared with risks of elective repeat cesarean delivery.

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.

Severe perineal trauma among women undergoing vaginal birth after cesarean delivery: A population-based cohort study.

BACKGROUND: To examine risk of severe perineal trauma among nulliparous women and those undergoing vaginal birth after cesarean delivery (VBAC). METHODS: This is a population-based cohort study of all births to women with their two first consecutive singleton pregnancies in Stockholm-Gotland Sweden between 2008 and 2014. Risk of severe perineal trauma was compared between nulliparous women and those undergoing VBAC with severe perineal trauma being the main outcome measure. Associations between indication and timing of primary cesarean delivery and risk of severe perineal trauma in subsequent vaginal birth were analyzed using Poisson regression analysis. RESULTS: The rate of severe perineal trauma among nulliparous women and those undergoing VBAC was 7.0% and 12.3%, respectively. Compared with nulliparous women, those undergoing VBAC were significantly older, had a shorter stature, and gave birth in a non-upright position to heavier infants with larger head circumferences. The rate of instrumental vaginal delivery among nulliparous women and those undergoing VBAC was 19.3% and 20.2%, respectively (P = 0.331). An increased risk of severe perineal trauma remained after adjustments among those undergoing VBAC (adjusted risk ratio 1.42, 95% CI 1.23-1.63). Level of risk was not associated with indication (dystocia or signs of fetal distress) of primary cesarean delivery, nor how far the woman had progressed in labor (fully dilated versus planned cesarean delivery) before delivering by cesarean. CONCLUSIONS: Compared with nulliparous women, those undergoing VBAC are at increased risk of severe perineal trauma, irrespective of indication and timing of primary cesarean delivery.

Validation of prediction model for successful vaginal birth after Cesarean delivery based on sonographic assessment of hysterotomy scar.

OBJECTIVE: To validate a prediction model for successful vaginal birth after Cesarean delivery (VBAC) based on sonographic assessment of the hysterotomy scar, in a Swedish population. METHODS: Data were collected from a prospective cohort study. We recruited non-pregnant women aged 18-35 years who had undergone one previous low-transverse Cesarean delivery at ≥ 37 gestational weeks and had had no other uterine surgery. Participants who subsequently became pregnant underwent transvaginal ultrasound examination of the Cesarean hysterotomy scar at 11 + 0 to 13 + 6 and at 19 + 0 to 21 + 6 gestational weeks. Thickness of the myometrium at the thinnest part of the scar area was measured. After delivery, information on pregnancy outcome was retrieved from hospital records. Individual probabilities of successful VBAC were calculated using a previously published model. Predicted individual probabilities were divided into deciles. For each decile, observed VBAC rates were calculated. To assess the accuracy of the prediction model, receiver-operating characteristics curves were constructed and the areas under the curves (AUC) were calculated. RESULTS: Complete sonographic data were available for 120 women. Eighty (67%) women underwent trial of labor after Cesarean delivery (TOLAC) with VBAC occurring in 70 (88%) cases. The scar was visible in all 80 women at the first-trimester scan and in 54 (68%) women at the second-trimester scan. AUC was 0.44 (95% CI, 0.28-0.60) among all women who underwent TOLAC and 0.51 (95% CI, 0.32-0.71) among those with the scar visible sonographically at both ultrasound examinations. CONCLUSION: The prediction model demonstrated poor accuracy for prediction of successful VBAC in our Swedish population. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Examination of the association of physical activity during pregnancy after cesarean delivery and vaginal birth among Chinese women.

BACKGROUND: The goal was to study whether higher physical activity can increase the success rate of Vaginal Birth after Cesarean Delivery (VBAC). METHODS: We enrolled 823 patients with previous cesarean section delivery history (between January 2015 and December 2017) and measured their physical activity during pregnancy. A final number of 519 patients were included for the trial of labor after cesarean delivery (TOLAC). All patients signed informed consent forms. RESULTS: We conducted bivariate analyses and identified that several variables were associated with successful VBAC: Prior history of vaginal birth (odds ratio [OR] 2.4, 95% CI 1.8-3.9); previous indication for primary cesarean delivery (OR 2.2, 95% CI 1.5-3.0); age younger than 40 years (OR 2.1, 95% CI 1.3-3.4); Weight gain less than 20 kg (OR 1.5, 95% CI 1.3-2.4); high pelvic/birth weight score (OR 1.4, 95% CI 1.1-2.0); no induction of labor (OR 1.9, 95% CI 1.4-2.8); and estimated prenatal fetal weight (OR 1.4, 95% CI 1.2-1.5). We also found that the bivariate association between physical activity and VBAC was significant (p = 0.002). In addition, there was higher odds of VBAC in women who had active physical activity of more than 150 min/week (adjusted OR 1.86, 95% CI 1.69-2.07). Lower odds of VBAC was associated with older age, weight gain during pregnancy, induction of labor, and having estimated prenatal fetal weight more than 3500 g. CONCLUSION: Physical activity during pregnancy may influence the success rate of VBAC in Chinese women. Future studies will be needed to prove the robustness of this association using more detailed exposure and outcome definitions.

Trial of labor following one previous cesarean delivery: the effect of gestational age.

PURPOSE: To stratify maternal and neonatal outcomes of trials of labor after previous cesarean delivery (TOLAC) by gestational age. METHODS: Retrospective cohort study of all singleton pregnancies with one previous cesarean delivery in TOLAC at term between 2007 and 2014. We compared outcomes of delivery at an index gestational week, with outcomes of women who remained undelivered at this index gestational week (ongoing pregnancy). Odds ratios and 95% confidence intervals were adjusted for maternal age, previous vaginal delivery, induction of labor, epidural use, presence of meconium, and birth weight > 4000 g. RESULTS: Overall, 2849 women were eligible for analysis. Of those, 2584 (90.7%) had a successful TOLAC and 16 women (0.56%) had uterine rupture. Those rates did not differ significantly for any gestational age (GA) group. Following adjustment for possible confounders, GA was not found to be independently associated with adverse maternal or neonatal outcomes. CONCLUSION: Among women at term with a single previous cesarean delivery, GA at delivery was not found to be an independent risk factor for TOLAC success or uterine rupture. We suggest that GA by itself will not serve as an argument for or against TOLAC.

Labor after cesarean delivery managed without induction or augmentation of labor.

BACKGROUND: This study aimed to describe the perinatal outcomes of women opting for vaginal birth after cesarean delivery (VBAC) managed without induction or augmentation of labor. METHODS: This was a retrospective cohort study of candidates for VBAC at a tertiary center in Japan from April 2003 to March 2012. Women with singleton gestations and one prior low-transverse cesarean delivery who intended VBAC at 36 weeks of gestation were identified as candidates for VBAC and included in the study. Participants were managed without induction or augmentation of labor. Maternal characteristics and perinatal outcomes were obtained from medical records. Factors associated with successful VBAC were analyzed with a multivariable logistic regression model. RESULTS: Of 333 candidates for VBAC, 242 (72.7%) had vaginal birth, 49 (14.7%) had repeat cesarean delivery with spontaneous labor, and 42 (12.6%) had repeat cesarean delivery without spontaneous labor. The rate of uterine rupture was 0.3% (1/333). Prior vaginal delivery and nonrecurring indications for prior cesarean delivery were associated with successful VBAC. CONCLUSIONS: Management of candidates for VBAC without induction or augmentation of labor resulted in a high VBAC rate and favorable perinatal outcomes. Such restrictive VBAC policies may be an acceptable alternative to standard management or abandonment of VBAC.

Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study.

BACKGROUND: Choice of delivery route after previous cesarean delivery can be difficult because both trial of labor after cesarean delivery and elective repeat cesarean delivery are associated with risks. The major risk that is associated with trial of labor after cesarean delivery is uterine rupture that requires emergency laparotomy. OBJECTIVE: This study aimed to estimate the occurrence of uterine rupture during trial of labor after cesarean delivery when lower uterine segment thickness measurement is included in the decision-making process about the route of delivery. STUDY DESIGN: In 4 tertiary-care centers, we prospectively recruited women between 34 and 38 weeks of gestation who were contemplating a vaginal birth after a previous single low-transverse cesarean delivery. Lower uterine segment thickness was measured by ultrasound imaging and integrated in the decision of delivery route. According to lower uterine segment thickness, women were classified in 3 risk categories for uterine rupture: high risk (<2.0 mm), intermediate risk (2.0-2.4 mm), and low risk (≥2.5 mm). Our primary outcome was symptomatic uterine rupture, which was defined as requiring urgent laparotomy. We calculated that 942 women who were undergoing a trial of labor after cesarean delivery should be included to be able to show a risk of uterine rupture <0.8%. RESULTS: We recruited 1856 women, of whom 1849 (99%) had a complete follow-up data. Lower uterine segment thickness was <2.0 mm in 194 women (11%), 2.0-2.4 mm in 217 women (12%), and ≥2.5 mm in 1438 women (78%). Rate of trial of labor was 9%, 42%, and 61% in the 3 categories, respectively (P<.0001). Of 984 trials of labor, there were no symptomatic uterine ruptures, which is a rate that was lower than the 0.8% expected rate (P=.0001). CONCLUSION: The inclusion of lower uterine segment thickness measurement in the decision of the route of delivery allows a low risk of uterine rupture during trial of labor after cesarean delivery.

A prediction model of vaginal birth after cesarean in the preterm period.

BACKGROUND: A validated model exists that predicts the probability of vaginal birth after cesarean delivery in patients at term who are undergoing a trial of labor after cesarean delivery. However, a model that predicts the success of a vaginal birth after cesarean delivery in the preterm period has not been developed. OBJECTIVE: We sought to develop and validate a predictive model for vaginal birth after cesarean delivery for women undergoing a trial of labor after cesarean delivery during the preterm period. STUDY DESIGN: We performed a secondary analysis of a prospective cohort study designed to evaluate perinatal outcomes in women with a prior cesarean scar. We included women with 1 prior low transverse cesarean delivery undergoing a trial of labor after cesarean delivery with a vertex singleton pregnancy in the preterm period (26-36 weeks). Using multivariable logistic regression modeling, we constructed a predictive model for vaginal birth after cesarean delivery with information known at admission for preterm delivery. Using a 70% to 30% random split of the data, the model was developed in the training data and subsequently confirmed in the validation data. Predictions and area under the curve were based on a 10-fold cross-validated jackknife estimation and based on 1000 bootstrap resampling methods. The adequacy of all models was evaluated based on the Hosmer-Lemeshow goodness-of-fit test. RESULTS: One thousand two hundred ninety-five women met our criteria for analysis. The significant predictors of vaginal birth after cesarean delivery success were chronic hypertension, hypertensive disease of pregnancy (gestational hypertension or preeclampsia), prior vaginal delivery, dilation on cervical examination at admission, prior vaginal birth after cesarean delivery, a recurring indication in a prior cesarean delivery, and induction of labor as well as a 2-way interactions between dilation and hypertensive disease of pregnancy, dilation and diabetes mellitus (pregestational or gestational), and induction of labor and hypertensive disease of pregnancy. The area under the curve from the prediction model was 0.80 (95% confidence interval, 0.77-0.83) and the model fit the data well (Hosmer-Lemeshow P = .367). The bootstrap and 10-fold cross-validated jackknife estimates of the corrected area under the curve of the model were 0.78 (95% confidence interval, 0.74-0.82) and 0.77 (95% confidence interval, 0.73-0.82), respectively, following incorporation of regression shrinkage. CONCLUSION: A cross-validated predictive model was created for patients undergoing a trial of labor after cesarean delivery in the preterm period using 8 variables known on admission. These factors were notably different from factors used in the model for term patients. This new model can be used to counsel patients in the preterm period who want to undergo a trial of labor after cesarean delivery on their predicted vaginal birth after cesarean delivery success.

Induction of labor versus expectant management for women with a prior cesarean delivery.

OBJECTIVE: Previous studies of induction of labor in the setting of trial of labor after cesarean have compared women undergoing trial of labor after cesarean to those undergoing spontaneous labor. However, the clinically relevant comparison is to those undergoing expectant management. The objective of this study was to compare obstetric outcomes between women undergoing induction of labor and those undergoing expectant management ≥39 weeks of gestation. STUDY DESIGN: This was a secondary analysis of data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network Cesarean Registry that included women with singleton gestations at a gestational age of ≥39 weeks and a history of 1 low transverse cesarean delivery. Outcomes of induction at 39, 40, and 41 weeks were compared to expectant management beyond each gestational age period using univariable and multivariable analyses. Women with scheduled repeat cesarean deliveries done for the indication of prior cesarean delivery were excluded from the analysis. RESULTS: In all, 12,676 women were eligible for analysis. The rate of vaginal birth after cesarean (VBAC) was higher among women undergoing induction of labor at 39 weeks compared to expectant management (73.8% vs 61.3%, P < .001). The risk of uterine rupture also was higher among women undergoing induction of labor at 39 weeks compared to expectant management (1.4% vs 0.5%, P = .006, respectively). In multivariable analysis, induction of labor at 39 weeks remained associated with a significantly higher chance of VBAC and uterine rupture (odds ratio, 1.31; 95% confidence interval, 1.03-1.67; and odds ratio, 2.73; 95% confidence interval, 1.22-6.12, respectively). CONCLUSION: Induction of labor at 39 weeks, when compared to expectant management, was associated with a higher chance of VBAC but also of uterine rupture.

Risk of uterine rupture among women attempting vaginal birth after cesarean with an unknown uterine scar.

OBJECTIVE: The purpose of this study was to estimate the association of uterine rupture and previous incision type, either unknown or low transverse, among women who attempt a trial of labor after 1 previous cesarean delivery. STUDY DESIGN: We conducted a secondary analysis of a prospective multicenter observational study of 15,519 women with term singletons who attempted a trial of labor after 1 previous cesarean delivery. Odds ratios for the association between uterine incision location, either unknown or low transverse, and uterine rupture were estimated with the use of multivariable logistic regression. RESULTS: Between 1999 and 2002, 99 of the 15,519 women (0.64%) who attempted a trial of labor after 1 previous cesarean delivery experienced a uterine rupture. Pregnant women with an unknown scar had lower odds of uterine rupture (adjusted odds ratio, 0.71; 95% confidence interval, 0.37-1.37) compared with women with a known low transverse scar. Other adverse maternal outcomes did not differ between the 2 groups of women. CONCLUSION: Among this cohort, women with an unknown uterine incision who attempted a trial of labor were not at increased risk of uterine rupture compared with women with a known low transverse incision.

Does midtrimester cervical length aid in predicting vaginal birth after cesarean?

OBJECTIVE: A longer midtrimester cervical length (CL) is associated with an increased chance of cesarean delivery, but CL has not been used to predict the chance of successful trial of labor after cesarean delivery (TOLAC). The objective of this study was to identify whether midtrimester CL improves the prediction of vaginal birth after cesarean delivery (VBAC) among women undergoing a TOLAC. STUDY DESIGN: Women with 1 prior cesarean and a singleton gestation in the vertex position who had a routine CL assessment between 18 and 24 weeks and chose to undergo a TOLAC were identified. Midtrimester CL and characteristics identifiable in early prenatal care that have been used in a validated predictive model for VBAC (ie, age, body mass index, race/ethnicity, prior vaginal delivery, prior VBAC, and indication for prior cesarean delivery) were abstracted from the medical record. Multivariable regressions with VBAC as the dependent variable, with and without CL, were created and their predictive capacity compared using receiver-operating characteristic curves and reclassification tables. RESULTS: Of the 678 women who met inclusion criteria, 517 (76.3%) experienced a VBAC. Mean midtrimester CL was lower in women who achieved a VBAC compared with those who required a cesarean delivery in labor (4.3 ± 0.8 cm vs 4.7 ± 0.8 cm, P < .001). In a multivariable logistic regression, midtrimester CL (centimeters) was significantly associated with a reduced chance of VBAC (adjusted odds ratio [aOR], 0.60; 95% confidence interval [CI], 0.47-0.76). Although the addition of CL improved the area under the receiver-operating characteristic curve (aOR, 0.695 [95% CI, 0.648-0.743] vs aOR, 0.727 [95% CI, 0.681-0.773]; P = .03), it did not significantly enhance the clinical value of the model, as quantified by net reclassification improvement (P = .11). CONCLUSION: Shorter midtrimester CL is associated with a greater chance of vaginal birth after a TOLAC. However, midtrimester CL does not significantly improve the clinical value of a previously developed VBAC prediction model.

[Changing trends and indications for cesarean section in the last few decades]. / A császármetszés javallatainak változása az elmúlt évtizedekben.

Cesarean section rates are increasing worldwide, which has been paralelled by an increase in primary cesarean delivery and decrease in vaginal birth after cesarean section. Behind the different frequencies there is a number of interrelated factors including advanced maternal age, increasing incidence of obesity, assisted reproductive technologies, and maternal request for non-medical reasons. The sub-optimal management of labor and the concerns about medical liability claims and litigations increase the number of abdominal deliveries. The author reviews the changing indications for cesarean deliveries in the last few decades and summarizes the effects on the obstetrical clinical practice.