Predicting vaginal birth after cesarean delivery: a review of prognostic factors and screening tools

Successful vaginal delivery and maternal and perinatal outcomes in patients with a history of cesarean section and labor trial: cross-sectional study

Objectives

To determine the proportion of successful vaginal deliveries in women with prior cesarean section; to describe maternal and perinatal complications; and to examine the factors associated with vaginal delivery.

Materials and methods

Descriptive cross-sectional study of women with a history of cesarean delivery, gestational age of more than 24 weeks, singleton live fetuses, with prior vaginal delivery who received care in a high complexity public institution in 2019. Patients with a history of more than one cesarean section or myomectomy were excluded. Consecutive sampling was used. Sociodemographic and obstetric variables, delivery route and maternal and perinatal complications were measured. A descriptive analysis as well as a multivariate exploratory analysis of the factors associated with successful vaginal delivery were carried out.

Results

Among 286 pregnant women included, the percentage of successful vaginal deliveries was 74.5 %. Maternal complications were identified in 3.2 % of vaginal delivery cases and in 6.8 % of cesarean births. Complications occurred in 1.3 % of all live neonates; there were 2 perinatal deaths. An association was found between successful vaginal delivery and a history of prior vaginal delivery (OR: 2.7; 95 % CI: 1.15-6.29); a Bishop score greater than 6 (OR: 2.2; 95 % CI: 1.03-4.56); spontaneous labor initiation (OR: 4.5; IC 95 % CI: 2.07-9.6); and maternal age under 30 years (OR:2.28; 95 % CI: 1.2-4.2).

Conclusions

Vaginal delivery is a safe option to consider in patients with prior cesarean section, in particular in cases of spontaneous labor initiation or prior vaginal delivery. Prospective cohorts are needed in order to confirm these findings.

Risk factor analysis in women who underwent trial of labor after cesarean section: a multicenter study in Germany

Objective

Rising caesarean delivery (CD) rates throughout the world are accompanied with high rates of severe maternal complications. The aim of the present study was to analyze the outcome of trial of labor after caesarean section (TOLAC) in a Western population and identify factors associated with the success of vaginal birth after caesarean section (VBAC).

Material and Methods

A retrospective study was performed at two large obstetric departments in Germany from 2008 to 2018. Women with singleton pregnancies, a history of only one previous CD with a low transverse incision, a viable fetus in cephalic presentation, and gestational age >32 weeks were included in the study. The characteristics and outcome of successful VBAC and failed TOLAC were compared. A subgroup analysis addressed gestational age, interpregnancy interval, fetal macrosomia, body mass index, and maternal age.

Results

Of 1,546 patients, 62.3% achieved VBAC while 37.7% had a secondary CD. Independent factors associated with the success of TOLAC were a history of vaginal birth in previous pregnancies (p<0.001) and the use of oxytocin (p<0.001), whereas preterm birth between gestational week 32 and 37 signified a higher risk of failed TOLAC (p=0.04). The success of VBAC did not differ significantly for patients older than 40 years of age, those with a shorter interpregnancy interval than 12 months, and fetal macrosomia with birth weight exceeding 4000 grams. Maternal and neonatal outcomes were poorer in women with failed TOLAC.

Conclusion

Nearly two thirds of women with a history of CD achieve VBAC in Germany. Previous vaginal birth and the augmentation of labor with oxytocin are positively associated with the achievement of VBAC and no major perinatal complications. The decision to have a TOLAC should be encouraged in the majority of patients. Further studies are needed to evaluate the feasibility of TOLAC in preterm delivery.

Maternal Morbidity and Birth Satisfaction After Implementation of a Validated Calculator to Predict Cesarean Delivery During Labor Induction

IMPORTANCE

A previously created and validated calculator provides an individualized cesarean delivery risk score for women undergoing labor induction. A higher predicted risk of cesarean delivery on the calculator has been associated with increased maternal and neonatal morbidity regardless of ultimate delivery mode. The effect of this calculator when implemented in clinical care has yet to be evaluated.

OBJECTIVE

To determine whether implementation of a validated calculator that predicts the likelihood of cesarean delivery at the time of labor induction is associated with maternal morbidity and birth satisfaction.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study used medical record review to compare the 1 year before calculator implementation (July 1, 2017, to June 30, 2018) with the 1 year after implementation (July 1, 2018, to June 30, 2019) at a US urban, university labor unit. Women admitted for labor induction with singleton gestation in cephalic presentation, intact membranes, and an unfavorable cervix were included. Data were analyzed from August 1, 2019, to September 13, 2020.

EXPOSURES

Patient and clinician knowledge of the calculated cesarean delivery risk score based on the validated calculator.

MAIN OUTCOMES AND MEASURES

The primary outcomes were (1) composite maternal morbidity defined by at least 1 of the following within 30 days of delivery: endometritis, postpartum hemorrhage (estimated or quantitative blood loss >1000 mL), blood transfusion, wound infection, venous thromboembolism, hysterectomy, intensive care unit admission, and readmission and (2) patient satisfaction assessed via Birth Satisfaction Scale-Revised (BSS-R) scores. Secondary outcomes included rate of cesarean delivery and neonatal morbidity.

RESULTS

A total of 1610 women were included in the analysis (788 in the preimplementation and 822 in the postimplementation periods) with a median age of 29 (interquartile range [IQR], 24-34) years. There were no significant baseline differences between groups except fewer inductions at a gestational age of 40 weeks or later in the postimplementation period (256 [31.1%] vs 298 [37.8%]). Calculator implementation was associated with decreased maternal morbidity overall, even when adjusting for confounders (141 [17.9%] vs 95 [11.6%]; adjusted absolute risk difference [aARD], -6.3%; 95% CI, -9.7% to -2.8%). Although there was no difference in birth satisfaction overall, calculator implementation was associated with improvements on items pertaining to quality of care provision (median BSS-R score, 19 [IQR, 16-20] vs 19 [IQR, 17-20]; P = .006). Calculator implementation was also associated with a decrease in cesarean delivery rate (228 [28.9%] vs 167 [20.3%]; aARD, -8.5% [95% CI, -12.6% to -4.5%]). There were no significant differences in neonatal morbidity.

CONCLUSIONS AND RELEVANCE

These findings suggest that implementation of a validated calculator to predict risk of cesarean delivery in clinical care is associated with reduced maternal morbidity. Implementation should occur broadly to determine whether calculator use improves national maternal outcomes.

The Association between Hospital Frequency of Labor after Cesarean and Outcomes in California

BACKGROUND

Labor after cesarean (LAC) is an alternative to planned repeat cesarean delivery. The effect of hospital-level factors on LAC frequency and vaginal birth after cesarean (VBAC) has been relatively understudied. It was our goal to determine if hospital frequency of LAC (number of women undergoing LAC/number of women with previous uterine scars) is associated with increased VBAC and associated outcomes among women undergoing LAC.

METHODS

We analyzed 43,331 term, singleton births to women who experienced LAC in California from 2007 to 2010. We conducted multivariable logistic regressions of infant and maternal outcomes for women at hospitals with high LAC frequency (≥median) compared with low LAC frequency (<median), adjusting for maternal and hospital characteristics. We stratified analyses by overall hospital birth volume (categories 1, low; 2, medium; 3, high).

RESULTS

We did not observe an association between high LAC frequency and VBAC in any category of hospital birth volume in regression models. We found that women in hospitals with high LAC frequency had higher odds of infection in category 1 (low) and 2 (medium) hospitals (category 1 hospitals adjusted odds ratio [aOR], 1.61; 95% confidence interval [CI], 1.04-2.48; category 2 hospitals, aOR, 2.12; 95% CI, 1.34-3.35) and postpartum hemorrhage in category 2 and 3 hospitals (category 2 hospitals: aOR, 2.49; 95% CI, 1.57-3.94; category 3 hospitals: aOR, 1.83; 95% CI, 1.24-2.70). We observed that high LAC frequency was associated with more adverse outcomes (e.g., infection, severe perineal lacerations, decreased Apgar scores) in category 2 than in category 1 and 3 hospitals.

CONCLUSIONS

We did not find that high LAC frequency was associated with more VBAC, nor with many perinatal complications in category 1 and 3 hospitals. The associations between high LAC frequency and both infection and postpartum hemorrhage are concerning and require further investigation. There may be a sensitive balance between increasing LAC access and determining appropriate LAC candidate selection.

Trial of labor after cesarean in older women who never delivered vaginally

OBJECTIVE

Maternal age is an established determinant of successful trial of labor after cesarean (TOLAC). While an increasing proportion of parturients are aged 40 years and older, and previously underwent a cesarean section, little data regarding TOLAC success for this age group is available. This study assessed TOLAC success, and its associated characteristics, among women >40 years who never delivered vaginally.

STUDY DESIGN

A retrospective case-control study of all women who never delivered vaginally aged ≥40 years with a history of previous cesarean delivery, who delivered at our hospital during 2006-2017. Maternal, neonatal, and delivery characteristics were compared between women with successful and unsuccessful TOLAC.

RESULTS

Of 335 older women who never delivered vaginally with a history of one cesarean delivery, 61 (18.2 %) elected TOLAC (18.2 %); the median age was 41[40-42] years and the inter-delivery interval 34 [25-50] months. Overall, 38/61 (62.3 %) had a successful TOLAC. Women with successful TOLAC had a higher rate of a non-recurrent indication for cesarean delivery in their previous cesarean delivery (42.1 % vs. 13.0 %, P = 0.01), whereas dysfunctional labor at previous delivery was more common in the failed TOLAC group (47.8 % vs. 15.8 %, P = 0.007). Failed TOLAC was associated with the presence of gestational diabetes (13.0 % vs. 0 %, P = 0.02) and having a comorbidity (47.8 % vs. 21.0 %, P = 0.02). Induction of labor at TOLAC was more common in the failed TOLAC group (34.8 % vs. 2.6 %, P < 0.001). Birthweight was higher in the failed TOLAC group (3330 vs. 3107 g, P = 0.04), as well as the birthweight difference between deliveries (212 g vs. 82 g, P = 0.03). Neonatal and maternal outcomes were comparable between groups, except for longer length of stay (5 vs. 4 days, P = 0.04) in the failed TOLAC group. In a multivariable logistic regression analysis, only two factors were independently associated with TOLAC failure: previous cesarean delivery due to dysfunctional labor (OR [95 % CI]: 13.40 (1.29, 138.71), P = 0.03) and higher inter-delivery birthweight difference (OR [95 % CI]: 1.18 (1.11, 1.39), P = 0.02).

CONCLUSIONS

TOLAC in older women who never delivered vaginally is associated with a moderate success rate. The indication for cesarean delivery at the first delivery and inter-delivery birthweight difference were identified as having strong predictive value for TOLAC outcome.

Risk score for failed trial of vaginal birth after a previous cesarean section including data of labor course

AIM

There is much discussion about the advantages and disadvantages of a trial of labor after cesarean (TOLAC). Some data suggest the greater the likelihood of success, the lower the risks of TOLAC. Our goal was to identify clinical and demographic variables associated with a failed TOLAC, available at admission for spontaneous labor and until 3 h later, with the aim of building two scores for risk of failed TOLAC.

METHODS

This is a nested case-control study with live births to women with one previous cesarean, in a public Brazilian teaching hospital. Preterm, induction, noncephalic presentations, twins, fetal malformations were excluded. Cases were failed TOLAC, and controls, the successful TOLAC. It was accessed the association of the cases with 20 variables (P < 0.05). Associated variables were tested in multivariate analysis to build the scores, which were internally validated.

RESULTS

We included 260 TOLAC, 42 cases and 218 controls. We found 11 variables associated with failed TOLAC. In the score to be applied at admission, we included hypertension, fundal height, previous vaginal birth and dilatation at admission. In the second score hypertension, fundal height at admission, membrane status and difference in dilatation 3 h after admission. Both scores presented good performance in the receiver-operator curve (areas under curve: 0.73 and 0.84, respectively). Both scores were translated into nomograms for clinical use.

CONCLUSION

Two scores were built for risk of failed TOLAC, to be applied at admission and 3 h later. We believe that choosing the more favorable cases makes risks of TOLAC lower.

Application of predictive model for vaginal birth after caesarean delivery

Medical practitioners are concerned with the selection of delivery mode after caesarean delivery. Several researchers have developed numerous models for predicting vaginal birth after caesarean delivery. This study selected seven widely used and representative advanced models, such as those of Grobman, Troyer and Parisi, Schoorel, Flamm, Gonen, Weinstain and Smith et al., analysed the constitutions and clinical applications of the models and identified the factors associated with patients to provide midwives a scientific reference for vaginal delivery evaluation of pregnant women after caesarean delivery.

Antenatal scoring system in predicting the success of planned vaginal birth following one previous caesarean section

This was a prospective observational study to determine the predictive factors for a successful vaginal birth after caesarean section (VBAC) and to develop a relevant antenatal scoring system. Patients with one previous caesarean section were included in this study. All data including maternal demographics, obstetric history, pregnancy progress and outcomes were collected and analysed. A total of 142 out of the 186 women (76.3%) had successful VBAC. History of previous vaginal delivery and non-recurrent indications for previous caesarean section were the significant predictive factors for a successful VBAC. Five variables for our scoring tool were selected. By using a proposed mean score of 4 out of 7, the scoring system had a sensitivity of 81.0%, specificity of 52.3% and a positive predictive value of 84.6%. VBAC antenatal scoring system was potentially a useful predictive tool in antenatal counselling. Impact statement What is already known on this subject: Planned vaginal birth after caesarean section (VBAC) is an important strategy to limit the overall caesarean section rate, which is related to maternal morbidities. However, trial of vaginal delivery does involve potential complications including scar dehiscence, postpartum haemorrhage and emergency hysterectomy. What the results of this study add: Clinical predictors of a successful VBAC include non-recurrent indications for the previous caesarean section, previous vaginal delivery, spontaneous onset of labour and birthweight less than 4kg. There were multiple screening tools developed to predict the likelihood of successful VBAC. These scoring systems involved various variables such as age, ethnicity, Bishop's score and previous caesarean indication. We had prospectively developed an antenatal scoring system based on five variables. Our result showed that patient with a score of four and above will have around 85% chance of successful VBAC. What the implications are of these findings for clinical practice and/or further research: We have also found that, estimated foetal weight based on ultrasound scan is a potential predictor for successful VBAC. This simple scoring method will be useful in-patient counselling regarding mode of delivery after one previous caesarean section. A multicentre study involving large cohort of patients is ideal to validate our scoring system.

Maternal and perinatal outcomes in women planning vaginal birth after caesarean (VBAC) at home in England: secondary analysis of the Birthplace national prospective cohort study

OBJECTIVE

To compare vaginal birth rates in women planning vaginal birth after caesarean (VBAC) at home versus in an obstetric unit (OU) and explore transfer rates in women planning home VBAC.

DESIGN

Prospective cohort study.

SETTING

OUs and planned home births in England.

POPULATION

1436 women planning VBAC in the Birthplace cohort, including 209 planning home VBAC.

METHODS

We used Poisson regression to calculate relative risks adjusted for maternal characteristics.

MAIN OUTCOME MEASURES

MAIN OUTCOMES

(i) vaginal birth and (ii) transfer from planned home birth to OU during labour or immediately after birth.

SECONDARY OUTCOMES

(i) composite of maternal blood transfusion or admission to higher level care, (ii) stillbirth or Apgar score <7 at 5 minutes, (iii) neonatal unit admission.

RESULTS

Planned VBAC at home was associated with a statistically significant increase in the chances of having a vaginal birth compared with planned VBAC in an OU (adjusted relative risk 1.15, 95% confidence interval 1.06-1.24). The risk of an adverse maternal outcome was around 2-3% in both settings, with a similar risk of an adverse neonatal outcome. Transfer rates were high (37%) and varied markedly by parity (para 1, 56.7% versus para 2+, 24.6%).

CONCLUSION

Women in the cohort who planned VBAC at home had an increased chance of a vaginal birth compared with those planning VBAC in an OU, but transfer rates were high, particularly for women with only one previous birth, and the risk of an adverse maternal or perinatal outcome was around 2-3%. No change in guidance can be recommended.

TWEETABLE ABSTRACT

Higher vaginal birth rates in planned VBAC at home versus in OU but 2-3% adverse outcomes and high transfer rate.

New insights on vaginal birth after cesarean: can it be predicted?

OBJECTIVE

To evaluate existing vaginal birth after cesarean (VBAC) screening tools and to identify additional factors that may predict VBAC or failed trial of labor.

DATA SOURCES

Relevant studies were identified through MEDLINE, Database of Abstracts of Reviews of Effectiveness, and the Cochrane databases (1980-September 2009), and from recent systematic reviews, reference lists, reviews, editorials, web sites, and experts.

METHODS OF STUDY SELECTION

Inclusion criteria limited studies to those of humans, written in English, studies conducted in the United States and developed countries, and those rated good or fair quality by the U.S. Preventive Services Task Force criteria. Studies of individual predictors were combined using a random effects model when the estimated odds ratios were comparable across included studies.

TABULATION, INTEGRATION, AND RESULTS

We identified 3,134 citations and reviewed 963 papers, of which 203 met inclusion criteria and were quality-rated. Twenty-eight provided evidence on predictors of VBAC and 16 presented information on scored models for predicting VBAC (or failed trial of labor). Six of the 11 scored models for predicting VBAC (or failed trial of labor) were validated by separated dataset, cross-validation, or both. Whereas accuracy remained high across all models for predicting VBAC, with predictive values ranging from 88% to 95%, accuracy for predicting failed trial of labor was low, ranging from 33% to 58%. Individual predictors including Hispanic ethnicity, African-American race, advanced maternal age, no previous vaginal birth history, birth weight heavier than 4 kg, and use of either augmentation or induction were all associated with reduced likelihood of VBAC.

CONCLUSION

Current scored models provide reasonable predictability for VBAC, but none provides consistent ability to identify women at risk for failed trial of labor. A scoring model is needed that incorporates known antepartum factors and can be adjusted for current obstetric factors and labor patterns if induction or augmentation is needed. This would allow women and clinicians to better determine individuals most likely to require repeat cesarean delivery.

Assessing cephalopelvic disproportion: back to the basics

Dystocia, or abnormally slow progress in labor, can result from cephalopelvic disproportion (CPD), malposition of the fetal head as it enters the birth canal, or ineffective uterine propulsive forces. Cephalopelvic disproportion occurs when there is mismatch between the size of the fetal head and size of the maternal pelvis, resulting in "failure to progress" in labor for mechanical reasons. Untreated, the consequence is obstructed labor that can endanger the lives of both mother and fetus. Despite the use of imaging technology in an attempt to predict CPD, there is poor correlation between radiologic pelvimetry and the clinical outcome of labor. Clinical pelvimetry still has a place in obstetrics for predicting or confirming CPD, but without appropriate training and repeated practice of this clinical skill, it is in danger of becoming a lost art. For this review, a computerized search of the terms cephalopelvic disproportion, dystocia, pelvimetry, obstructed labor, and malposition was done using MEDLINE, PUBMED, SCOPUS, and CINAHL, and historical articles, texts, articles from indexed journals, and references cited in published works were also reviewed.

Vaginal birth after cesarean: clinical risk factors associated with adverse outcome

OBJECTIVE

The objective of the study was to identify vaginal birth after cesarean (VBAC) success rates and maternal and neonatal complication rates for selected antenatal conditions.

STUDY DESIGN

This was a population-based cohort study using administrative discharge data for women delivering in California hospitals during 2002.

RESULTS

Among 41,450 women, 29.72% (12,320 of 41,450) had maternal, fetal, or placental conditions complicating pregnancy. Attempted VBAC rates and VBAC success rates varied widely by these clinical condition, ranging from 10% to 73%. The VBAC success rate for low-risk women (no conditions) was 73.76% vs 50.31% for high-risk women (at least 1 condition), P < .0001. Absolute rates of maternal and neonatal complications were low (less than 1-2%), and the rate of adverse events was higher in the high-risk clinical group as compared with the low-risk clinical group.

CONCLUSION

Variation in rates of VBAC success and childbirth morbidities can be partially attributed to clinical factors complicating pregnancy. Women without such conditions show improved VBAC success and fewer maternal and neonatal complications.

Effect of hospital volume on maternal outcomes in women with prior cesarean delivery undergoing trial of labor

The authors examined the association between hospital volume of vaginal birth after cesarean section (VBAC) and VBAC failure, uterine rupture, and maternal morbidity. This was a secondary analysis of data from a retrospective cohort study carried out from 1995 to 2000. Trained nurses extracted detailed information from the medical records of more than 25,000 women with a prior cesarean delivery from 17 community and tertiary-care hospitals in the northeastern United States. The study sample included 12,844 women with prior cesarean section who attempted vaginal delivery with a singleton birth. Annual hospital VBAC volume was divided into tertiles. Primary outcomes included VBAC failure, uterine rupture, and a composite measure of maternal morbidity. The authors used multivariable logistic regression to assess the association between hospital VBAC volume and adverse VBAC outcomes after controlling for confounders. The authors did not find evidence of an association between hospital VBAC volume and the likelihood of adverse outcomes in VBAC after adjustment for patient mix. Other risk factors consistent with prior research were identified, including induction of labor, >/=2 prior cesarean deliveries, preeclampsia, diabetes mellitus, and high birth weight. Prior vaginal delivery was protective against adverse VBAC outcomes. The risk of an adverse VBAC outcome in low-volume hospitals was comparable to that in high-volume hospitals.

Tailoring systematic reviews to meet critical priorities in maternal health in the intrapartum period

Health care practitioners and researchers commonly call for greater reliance on evidence as a means to achieve improvement in quality of care. Systematic reviews provide a means to accelerate the use of evidence-based clinical interventions and public health practices. The extent to which these time- and resource-intensive systematic reviews currently address critical maternal health priorities in the intrapartum period is unclear. This analysis summarises key maternal health and research priorities, maps these priorities to existing reviews, identifies gaps in the literature that can be addressed with systematic reviews, and highlights key methodological concerns in conducting systematic reviews. The analysis draws on published data on maternal morbidities and an overview of 108 systematic reviews in Medline in the past 5 years using the MeSH terms 'Delivery, Obstetric,' to draw the links between health priorities, research priorities, existing evidence and missing evidence. Key causes of morbidity during labour and delivery in the United States include haemorrhage, pre-eclampsia and eclampsia, obstetric trauma and infection. Analyses of maternal morbidity and mortality suggest that key concerns include racial and ethnic disparities in health outcomes and the prevention of adverse events. Systematic reviews, however, generally tend to focus on the reduction of harms associated with interventions, are frequently limited to randomised designs, and do not address issues of health disparities. The results suggest that advances in evidence-based care in maternal health require that systematic reviews address issues of prevention of adverse events, include a larger variety of study designs when necessary and pay closer attention to health disparities.

Temporal trends in the rates of trial of labor in low-risk pregnancies and their impact on the rates and success of vaginal birth after cesarean delivery

OBJECTIVE

The national rate of vaginal birth after cesarean delivery decreased by 55% between 1996 and 2002. The objective of this investigation was to determine, in our population in upstate New York, whether this decline in the vaginal birth after cesarean delivery rate was due to temporal changes in the trial of labor rates or in the vaginal birth after cesarean delivery success rates.

STUDY DESIGN

Regional perinatal databases were used to obtain birth certificate data from a total of 135,833 live births in upstate New York from 1998 to 2002. Trial of labor, vaginal birth after cesarean delivery, and vaginal birth after cesarean delivery success rates were calculated for the 11,446 women who had had a previous cesarean delivery and a singleton, low-risk pregnancy at > or = 37 weeks of gestation. Additional factors that were analyzed included age, race, education, insurance, body mass index, parity, gestation, area of residence, prenatal care provider, size of hospital, and level of newborn nursery specialization. Tests for trends were conducted by year for each of the variables.

RESULTS

The trial of labor rate declined 39% from 58.7 in 1998 to 35.7 per 100 eligible women in 2002 (P < .01). The decline in trial of labor rates persisted after stratification within almost all groups (P < .01). The overall vaginal birth after cesarean delivery rate decreased 44%, from 42.7 in 1998 to 24.1 per 100 eligible women in 2002 (P < .01). The decline in vaginal birth after cesarean delivery rates persisted after stratification within almost all groups (P < .01). The rate of vaginal birth after cesarean delivery success was unchanged from 1998 to 2002 (P = not significant).

CONCLUSION

We found a major decline in trial of labor and vaginal birth after cesarean delivery rates in low-risk women from 1998 to 2002. There was no change in vaginal birth after cesarean delivery success in those patients who attempted trial of labor. This suggests that the decline in the vaginal birth after cesarean delivery rates that have been observed nationally may be due to a decline in trial of labor attempts and not to a change in vaginal birth after cesarean delivery success rates. The steep declines in trial of labor attempts and vaginal birth after cesarean deliveries suggest that there was a rapid change in the perception of optimal treatment practices for these patients by obstetricians.

Predicting cesarean section and uterine rupture among women attempting vaginal birth after prior cesarean section

BACKGROUND

There is currently no validated method for antepartum prediction of the risk of failed vaginal birth after cesarean section and no information on the relationship between the risk of emergency cesarean delivery and the risk of uterine rupture.

METHODS AND FINDINGS

We linked a national maternity hospital discharge database and a national registry of perinatal deaths. We studied 23,286 women with one prior cesarean delivery who attempted vaginal birth at or after 40-wk gestation. The population was randomly split into model development and validation groups. The factors associated with emergency cesarean section were maternal age (adjusted odds ratio [OR] = 1.22 per 5-y increase, 95% confidence interval [CI]: 1.16 to 1.28), maternal height (adjusted OR = 0.75 per 5-cm increase, 95% CI: 0.73 to 0.78), male fetus (adjusted OR = 1.18, 95% CI: 1.08 to 1.29), no previous vaginal birth (adjusted OR = 5.08, 95% CI: 4.52 to 5.72), prostaglandin induction of labor (adjusted OR = 1.42, 95% CI: 1.26 to 1.60), and birth at 41-wk (adjusted OR = 1.30, 95% CI: 1.18 to 1.42) or 42-wk (adjusted OR = 1.38, 95% CI: 1.17 to 1.62) gestation compared with 40-wk. In the validation group, 36% of the women had a low predicted risk of caesarean section (< 20%) and 16.5% of women had a high predicted risk (> 40%); 10.9% and 47.7% of these women, respectively, actually had deliveries by caesarean section. The predicted risk of caesarean section was also associated with the risk of all uterine rupture (OR for a 5% increase in predicted risk = 1.22, 95% CI: 1.14 to 1.31) and uterine rupture associated with perinatal death (OR for a 5% increase in predicted risk = 1.32, 95% CI: 1.02 to 1.73). The observed incidence of uterine rupture was 2.0 per 1,000 among women at low risk of cesarean section and 9.1 per 1,000 among those at high risk (relative risk = 4.5, 95% CI: 2.6 to 8.1). We present the model in a simple-to-use format.

CONCLUSIONS

We present, to our knowledge, the first validated model for antepartum prediction of the risk of failed vaginal birth after prior cesarean section. Women at increased risk of emergency caesarean section are also at increased risk of uterine rupture, including catastrophic rupture leading to perinatal death.

The Effect of Prematurity on Vaginal Birth After Cesarean Delivery: Success and Maternal Morbidity

OBJECTIVE

We sought to compare vaginal birth after cesarean (VBAC) success and uterine rupture rates between preterm and term gestations in women with a history of one prior cesarean delivery. Our hypothesis was that preterm women undergoing VBAC were more likely to be successful and have a lower rate of complications than term women undergoing VBAC.

METHODS

We reviewed medical records of women with a history of a cesarean delivery who either attempted a VBAC or underwent a repeat cesarean delivery from 1995 through 2000 in 17 community and university hospitals. We collected information on demographics, medical and obstetric history, complications, and outcome of the index pregnancy. The primary analysis was limited to women with singleton gestations and one prior cesarean delivery. Statistical analysis consisted of bivariate and multivariable techniques.

RESULTS

Among the 20,156 patients with one prior cesarean delivery, 12,463 (61%) attempted a VBAC. Mean gestational ages for the term and preterm women were 39.2 weeks and 33.9 weeks of gestation, respectively. The VBAC success rates for the term and preterm groups were 74% and 82%, respectively (P < .001). Multivariable analysis showed that the VBAC success was higher (adjusted odds ratio 1.54, 95% confidence interval 1.27-1.86) in preterm gestations. A decreased risk of rupture among preterm gestations was suggested in these results (adjusted odds ratio 0.28, 95% confidence interval 0.07-1.17; P = .08).

CONCLUSION

Preterm patients undergoing a VBAC have higher success rates when compared with term patients undergoing a VBAC. Preterm patients undergoing VBAC may have lower uterine rupture rates.

Evidence-based vaginal birth after Caesarean section

Caesarean section rates are rising globally. Whether vaginal birth after Caesarean (VBAC) is safe and under what circumstances is increasingly important. This chapter reviews the literature about the risks of VBAC, patient and management factors that may alter risk, and discusses ongoing research as well as suggestions for improving future research.