Predictors of vaginal delivery in medically indicated early preterm induction of labor

External validation and updating of the Rossi nomogram for predicting cesarean delivery following induction: is the Bishop score valuable?

OBJECTIVE

This study sought to validate the Rossi nomogram in a Chinese population and then to include the Bishop score to see if it has an effect on the accuracy of the nomogram.

MATERIALS AND METHODS

The Rossi predictive model was applied and externally validated in a retrospective cohort from August 2017 and July 2023 in a Chinese tertiary-level medical center. For the revision and updating of the models, the regression coefficients of all the predictors (except race) were re-estimated and then the cervical Bishop score at the time of induction was added. Each model's performance was measured using the receiver-operating characteristic and calibration plots. Decision curve analysis determined the range of the probability threshold for each prediction model that would be of clinical value.

RESULTS

A total of 721 women met the inclusion criteria, of whom 183 (25.4%) underwent a cesarean delivery. The calibration demonstrated the underestimation of the original model, with an area under the curve (AUC) of 0.789 (95% confidence interval [CI] 0.753-0.825, p < 0.001). After recalibrating the original model, the discriminative performance was improved from 0.789 to 0.803. Moreover, the discriminatory power of the updated model was further improved when the Bishop score at the time of induction was added to the recalibrated multivariable model. Indeed, the updated model demonstrated good calibration and discriminatory power, with an AUC of 0.811. The decision curve analysis indicated that all the models (original, recalibrated, and updated) provided higher net benefits of between 0 and 60% of the probability threshold, which indicates the benefits of using the models to make decisions concerning patients who fall within the identified range of the probability threshold. The net benefits of the updated model were higher than those of the original model and the recalibrated model.

CONCLUSION

The nomogram used to predict cesarean delivery following induction developed by Rossi et al. has been validated in a Chinese population in this study. More specifically, adaptation to a Chinese population by excluding ethnicity and including the Bishop score prior to induction gave rise to better performance. The three models (original, recalibrated, and updated) offer higher net benefits when the probability threshold is between 0 and 60%.

Prediction of successful labor induction with very unfavorable cervix: A comparison of six scores

OBJECTIVE

To compare the ability of six scoring systems to predict successful labor induction with cervical ripening among women with a Bishop score <3.

METHODS

Secondary analysis of data from a prospective, multicenter observational Methods of Induction of Labor and Perinatal Outcomes (MEDIP) cohort study in 94 obstetrical French units. We included women with a Bishop score <3 before cervical ripening. We compared six scores: Bishop, simplified Bishop, modified Bishop, simplified Bishop including parity, Hughey, and Levine scores. Vaginal delivery defined successful labor induction. The ability of each score to predict successful labor induction was evaluated by comparing their area under the curve (AUC).

RESULTS

Among the 600 eligible women in this study, 408 (68%) delivered vaginally. Body mass index (calculated as weight in kilograms divided by the square of height in meters; mean ± standard deviation [SD]: 24.7 ± 5.5 vs 26.0 ± 5.7; P = 0.01) and nulliparity (48.8% vs 85.4%; P < 0.001) were lower in the successful induction group, whereas height was higher (mean ± SD: 165.3 ± 6.0 cm vs 163.7 ± 6.0 cm; P = 0.002). The simplified Bishop including parity, Hughey, and Levine scores had the highest AUC (0.70, 95% confidence interval [CI] 0.65-0.73; 0.68, 95% CI 0.64-0.74; and 0.69, 95% CI 0.65-0.74, respectively).

CONCLUSION

In women with a very unfavorable cervix, scores that include parity predict successful labor induction more accurately, such as simplified Bishop including parity, Hughey, or Levine scores.

Delivery outcomes after induction of labor among women with hypertensive disorders of pregnancy

OBJECTIVE

Induction of labor is known to be safe and highly effective in low-risk women. However, only limited research considers the relative success rates of induction of labor among women with one or more obstetric comorbidities. Our objective was to determine if the risk of cesarean delivery after induction of labor (IOL) is increased in women with a spectrum of hypertensive disorders of pregnancy compared to women with normotensive pregnancies.

STUDY DESIGN

We analyzed data from 1842 women undergoing IOL occurring at Grady Memorial Hospital in Atlanta, Georgia 2016-2018. We used multivariable log binomial models to estimate unadjusted and adjusted risk ratios (aRR) describing the association between hypertensive disorder diagnosis (preeclampsia with or without severe features, gestational hypertension, and chronic hypertension) and cesarean delivery, adjusting for demographics, pre-pregnancy conditions, and gestational age at delivery.

RESULTS

Overall, 44% (n = 808) of women in our study were diagnosed with any hypertensive disorder. Among women with hypertensive disorders, 74% had a successful vaginal delivery after IOL as compared to 82% of women without a hypertensive disorder. In the fully adjusted model, women with preeclampsia with severe features (aRR: 1.6, 95% CI: (1.3, 2.0)) and chronic hypertension had the largest risk for cesarean delivery (aRR 1.3, 95% CI: 0.9, 1.7)) compared with women with a normotensive pregnancy.

CONCLUSION

Our study suggests that while patients with certain hypertensive diagnoses may be at increased risk for cesarean delivery following IOL, most patients with hypertensive disorders were still able to undergo a successful vaginal delivery following IOL.

Labour induction in twin pregnancies

Medically-indicated deliveries are common in twin pregnancies given the increased risk of various obstetric complications in twin compared to singleton pregnancies, mainly hypertensive disorders of pregnancy and foetal growth restriction. Due to the unique characteristics of twin pregnancies, the success rates and safety of labour induction may be different than in singleton pregnancies. However, while there are abundant data regarding induction of labour in singleton pregnancies, the efficacy and safety of labour induction in twin pregnancies have been far less studied. In the current manuscript we summarize available data on various aspects of labour induction in twin pregnancies including incidence, success rate, prognostic factors, safety and methods for labour induction in twins. This information may assist healthcare providers in counselling patients with twin pregnancies when labour induction is indicated.

Risk of caesarean delivery in labour induction: a systematic review and external validation of predictive models

BACKGROUND

Despite the existence of numerous published models predicting the risk of caesarean delivery in women undergoing induction of labour (IOL), validated models are scarce.

OBJECTIVES

To systematically review and externally assess the predictive capacity of caesarean delivery risk models in women undergoing IOL.

SEARCH STRATEGY

Studies published up to 15 January 2021 were identified through PubMed, CINAHL, Scopus and ClinicalTrials.gov, without temporal or language restrictions.

SELECTION CRITERIA

Studies describing the derivation of new models for predicting the risk of caesarean delivery in labour induction.

DATA COLLECTION AND ANALYSIS

Three authors independently screened the articles and assessed the risk of bias (ROB) according to the prediction model risk of bias assessment tool (PROBAST). External validation was performed in a prospective cohort of 468 pregnancies undergoing IOL from February 2019 to August 2020. The predictive capacity of the models was assessed by creating areas under the receiver operating characteristic curve (AUCs), calibration plots and decision curve analysis (DCA).

MAIN RESULTS

Fifteen studies met the eligibility criteria; 12 predictive models were validated. The quality of most of the included studies was not adequate. The AUC of the models varied from 0.520 to 0.773. The three models with the best discriminative capacity were those of Levine et al. (AUC 0.773, 95% CI 0.720-0.827), Hernández et al. (AUC 0.762, 95% CI 0.715-0.809) and Rossi et al. (AUC 0.752, 95% CI 0.707-0.797).

CONCLUSIONS

Predictive capacity and methodological quality were limited; therefore, we cannot currently recommend the use of any of the models for decision making in clinical practice.

TWEETABLE ABSTRACT

Predictive models that predict the risk of cesarean section in labor inductions are currently not applicable.

FIGO (international Federation of Gynecology and obstetrics) initiative on fetal growth: best practice advice for screening, diagnosis, and management of fetal growth restriction

Fetal growth restriction (FGR) is defined as the failure of the fetus to meet its growth potential due to a pathological factor, most commonly placental dysfunction. Worldwide, FGR is a leading cause of stillbirth, neonatal mortality, and short- and long-term morbidity. Ongoing advances in clinical care, especially in definitions, diagnosis, and management of FGR, require efforts to effectively translate these changes to the wide range of obstetric care providers. This article highlights agreements based on current research in the diagnosis and management of FGR, and the areas that need more research to provide further clarification of recommendations. The purpose of this article is to provide a comprehensive summary of available evidence along with practical recommendations concerning the care of pregnancies at risk of or complicated by FGR, with the overall goal to decrease the risk of stillbirth and neonatal mortality and morbidity associated with this condition. To achieve these goals, FIGO (the International Federation of Gynecology and Obstetrics) brought together international experts to review and summarize current knowledge of FGR. This summary is directed at multiple stakeholders, including healthcare providers, healthcare delivery organizations and providers, FIGO member societies, and professional organizations. Recognizing the variation in the resources and expertise available for the management of FGR in different countries or regions, this article attempts to take into consideration the unique aspects of antenatal care in low-resource settings (labelled “LRS” in the recommendations). This was achieved by collaboration with authors and FIGO member societies from low-resource settings such as India, Sub-Saharan Africa, the Middle East, and Latin America.

Customized Probability of Vaginal Delivery With Induction of Labor and Expectant Management in Nulliparous Women at 39 Weeks of Gestation

OBJECTIVE

To develop models to predict vaginal delivery in low-risk, nulliparous women contemplating elective induction of labor or expectant management at 39 weeks of gestation.

METHODS

We conducted a secondary analysis of a randomized controlled trial of planned elective induction of labor at 39 weeks of gestation compared with expectant management for low-risk nulliparous women. Two groups were included for this analysis: 1) women who were randomized to the induction of labor group and underwent elective induction at 39 0/7-39 4/7 weeks of gestation and 2) women who were randomized to the expectant management group who experienced spontaneous labor or medically indicated delivery (including postterm). Multivariable logistic regression models were developed for each group using patient characteristics that would be available at the time of counseling. Model selection was based on k-fold cross-validation using backward elimination and variables that remained significant at P<.05 were retained. To compare estimated with observed rates, the elective induction of labor model was then applied to each woman in both groups to estimate individualized predicted probabilities of vaginal delivery with elective induction of labor.

RESULTS

Of 6,106 women enrolled in the trial, 4,661 met criteria for this analysis. Vaginal delivery occurred in 80.6% of the 2,153 women in the elective induction of labor group and 77.2% of the 2,508 women in the expectant management group (P=.005). The final elective induction of labor model included age, height, weight, and modified Bishop score (area under the receiver operating characteristic curve [AUROC] 0.72, 95% CI 0.70-0.75). The same variables were included in the final expectant management model (AUROC 0.70, 95% CI 0.67-0.72). Across the range of predicted probability deciles derived from the elective induction of labor model, almost all women who underwent elective induction of labor at 39 weeks of gestation had a higher observed chance of vaginal delivery than expectant management.

CONCLUSION

Irrespective of the individual predicted chance of vaginal delivery from elective induction of labor at 39 weeks of gestation, vaginal delivery is generally more frequent if elective induction of labor is undertaken rather than expectant management. These data can be used to counsel nulliparous women regarding their "customized" chances of vaginal delivery as they choose between elective induction of labor or expectant management at 39 weeks of gestation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT01990612.

Prediction Model for Vaginal Birth After Induction of Labor in Women With Hypertensive Disorders of Pregnancy

OBJECTIVE

To identify characteristics associated with vaginal delivery compared with cesarean delivery after labor induction among women with hypertensive disorders of pregnancy and to develop and validate a prediction model to assist in clinical care.

METHODS

We studied a retrospective cohort of women with singleton pregnancies who had hypertensive disorders of pregnancy and who underwent induction of labor at 34 weeks of gestation or more from January 1, 2002, to March 31, 2013. Exclusion criteria included spontaneous labor, prelabor cesarean delivery, and known fetal anomalies. The study cohort was randomly divided into two groups; 70% of pregnancies were used to identify characteristics associated with vaginal delivery and develop a prediction model, and 30% were used to internally validate the model. Candidate predictors were limited to those associated with cesarean delivery and were available to a practitioner at time of induction. Stepwise backward logistic regression was used to build the most parsimonious model predicting cesarean delivery. Hosmer-Lemeshow test was used to assess goodness-of-fit. Model discrimination was evaluated using the concordance index and displayed through the area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 1,357 women meeting study criteria, 974 (71.8%) had a vaginal delivery. The final model consisted of eight variables: maternal age, body mass index, gestational age, intrapartum magnesium sulfate for seizure prophylaxis, need for cervical ripening, prior cesarean delivery and cervical dilation, and effacement. Model calibration and discrimination were satisfactory with Hosmer-Lemeshow test P=.35 and with a 95% CI, an AUC of 0.76 (0.73-0.79). Among those with predicted probability of cesarean delivery of 20% or less, 89.5% had a vaginal delivery. Internal validation demonstrated similar discriminatory ability.

CONCLUSION

Using information available before labor induction, and contingent on future external validation, our model can help women better understand their likelihood of vaginal delivery success when undergoing induction of labor for hypertensive disorders of pregnancy.

Externally Validated Prediction Model of Vaginal Delivery After Preterm Induction With Unfavorable Cervix

OBJECTIVE

To create and externally validate a predictive model to calculate the likelihood of vaginal delivery after preterm induction with unfavorable cervix.

METHODS

This was a retrospective cohort study of women with a singleton gestation from a single academic institution who underwent an induction of labor at less than 37 weeks of gestation from January 2009 to June 2018. Women with contraindications for vaginal delivery were excluded. Analyses were limited to women with unfavorable cervix (both simplified Bishop score [dilation, station, and effacement: range 0-9] less than 6 and cervical dilation less than 3 cm). A stepwise logistic regression analysis was used to identify the factors associated with vaginal delivery by considering maternal characteristics and comorbidities as well as fetal conditions. The final model was validated using an external data set of the Consortium on Safe Labor after applying the same inclusion and exclusion criteria. We compared the area under the curve (AUC) of our predictive model and the simplified Bishop score.

RESULTS

Of the 835 women, 563 (67%) had vaginal delivery. Factors associated with vaginal delivery included later gestational age at delivery, higher parity, more favorable simplified Bishop score, and preterm prelabor rupture of membranes. Factors including older maternal age, non-Hispanic Black race, higher body mass index, and abruption were associated with decreased likelihood of vaginal delivery. In the external validation cohort, 1,899 women were analyzed, of whom 1,417 (75%) had vaginal delivery. The AUCs of simplified Bishop score and the final model were 0.65 (95% CI 0.59-0.66) and 0.73 (95% CI 0.72-0.79), respectively, for the external validation cohort. The online calculator was created and is available at www.medstarapps.org/obstetricriskcalculator/ and in the Obstetric Risk Calculator mobile application in the Apple App Store and Google Play Store.

CONCLUSION

Our externally validated model was efficient in predicting vaginal delivery after preterm induction with unfavorable cervix.

Risk factors for Cesarean delivery in pregnancy with small-for-gestational-age fetus undergoing induction of labor

OBJECTIVES

To identify risk factors for Cesarean delivery and non-reassuring fetal heart tracing (NRFHT) in pregnancies with a small-for-gestational-age (SGA) fetus undergoing induction of labor and to design and validate a prediction model, combining antenatal and intrapartum variables known at the time of labor induction, to identify pregnancies at increased risk of Cesarean delivery.

METHODS

This was a retrospective cohort study of non-anomalous, singleton gestations with a SGA fetus that underwent induction of labor, delivered in a single tertiary referral center between January 2011 and December 2016. SGA was defined as estimated fetal weight (EFW) < 10^th percentile. The primary outcome was to identify risk factors associated with Cesarean delivery. The secondary outcome was to identify risk factors associated with NRFHT. Univariate and multivariate analyses were used to determine which clinical characteristics, available at the time of admission, had the strongest association with Cesarean delivery and NRFHT during labor induction. The predictive value of the final models was assessed by the area under the receiver-operating-characteristics curve (AUC). Sensitivity and specificity of the models were also assessed. Internal validation of the models was performed using 10 000 bootstrap replicates of the original cohort. The adequacy of the models was evaluated using the Hosmer-Lemeshow goodness-of-fit test.

RESULTS

A total of 594 pregnancies were included. Cesarean delivery was performed in 243 (40.9%) pregnancies. Significant risk factors associated with Cesarean delivery, and included in the final model, were maternal age, gestational age at delivery and initial method of labor induction. The bootstrap estimate of the AUC of the final prediction model for Cesarean delivery was 0.82 (95% CI, 0.78-0.86). The model had sensitivity of 64.2%, specificity of 86.9%, positive likelihood ratio (LR) of 4.9 and negative LR of 0.41. The model had good fit (P = 0.617). NRFHT complicated 117 (19.7%) pregnancies. Significant risk factors for NRFHT included EFW < 5^th percentile, abnormal umbilical artery Doppler studies (pulsatility index > 95^th percentile or absent/reversed end-diastolic flow) and gestational age at delivery. The final prediction model for NRFHT had an AUC of 0.69 (95% CI, 0.63-0.75) and specificity of 97.0%.

CONCLUSION

We identified several significant risk factors for Cesarean delivery and NRFHT among SGA pregnancies undergoing induction of labor. Clinicians may use these risk factors to guide patient counseling and to help anticipate the potential need for operative delivery. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prediction models for determining the success of labor induction: A systematic review

INTRODUCTION

The purpose of this study was to systematically identify and compare clinical models using universally accessible clinical and demographic factors that were derived and/or validated to predict the success of labor induction with a view to making recommendations for practice.

MATERIAL AND METHODS

MEDLINE, Embase, www.clinicaltrials.gov, and PubMed (for non-MEDLINE and studies in-progress) were searched from inception to November 2017. Only studies that derived and/or validated clinical prediction models using variables obtained through antenatal history and digital cervical examination were included. Two reviewers independently screened titles and abstracts and extracted data from eligible studies into a standardized form. Extracted data included: participant characteristics, sample size, variables considered and included, endpoint definitions, study design and model performance. The Prediction Study Risk of Bias Assessment Tool (PROBAST) was used to appraise included studies. In view of clinical and methodologic heterogeneity between studies, only descriptive analysis was possible. The protocol was registered with the PROSPERO International prospective register of systematic reviews [CRD42017081548].

RESULTS

The search identified 16 studies describing 14 prediction models derived between 1966 and 2018. Models varied and demonstrated major limitations with regard to methodology, scope and performance. Of the derived models, six were internally validated and three were externally validated. Performance was most commonly measured using the area under the receiver operator characteristic curve, which ranged from 0.68 to 0.79, 0.67 to 0.77 and 0.61 to 0.73 for derived, internally validated and externally validated models, respectively. The risk-of-bias of included studies ranged from some studies fulfilling only 36% and some others fulfilling 86% of eligible PROBAST items.

CONCLUSIONS

No published model can be recommended for use at the bedside to determine the success of vaginal birth after labor induction. Based on the limitations of included models, a list of recommendations for improving model performance and utilization is provided, as well as measures for encouraging appropriate use of prediction models. The attitudes of women and care providers, and the clinical and resource implications must be explored prior to recommending the use of prediction models for determining the success of labor induction.

Hypertensive Disorders in Pregnancy

Hypertensive disorders of pregnancy are a heterogeneous group of conditions that include chronic hypertension, gestational hypertension, preeclampsia, and preeclampsia superimposed on chronic hypertension. These disorders account for a significant proportion of perinatal morbidity and mortality nearly 10% of all maternal deaths in the United States. Given the substantial health burden of hypertensive disorders in pregnancy, there is increasing interest in optimizing management of these conditions. This article summarizes the diagnosis and management of each of the disorders in the spectrum of hypertension in pregnancy and highlights recent updates in the field.

[Maternal outcomes in case of cesarean before 32weeks of gestation: A retrospective observational study]

OBJECTIVES

In recent years, active neonatal care in case of prematurity leads to an increase of cesarean delivery rate. Data remains sparse on maternal morbidity induced by preterm cesareans and especially before 32 weeks of gestation. The main aim of this study was to evaluate per-partum maternal morbidity in case of cesarean performed before 32 week of gestation. As secondary objectives, we assessed post-partum maternal morbidity and factors associated with maternal morbidity.

METHODS

This is a retrospective single-center study conducted in a tertiary care unit between 2014 and 2016 including cesareans performed before 32 week of gestation in the study period. The primary outcome was a composite criterion of per partum maternal morbidity including post-partum hemorrhage, blood transfusion, general anesthesia, surgical wounds and maternal death. The secondary outcome was the post-partum maternal morbidity, defined by a composite criterion including hospitalization more than 7 days, infectious disease, wall and digestive complication and venous thromboembolic disease.

RESULTS

Two hundred and eleven women were included. Maternal morbidity occurred in 21.3% in per partum and in 20.4% in post-partum. The factors associated with per partum morbidity were low-lying placenta (OR=4.40 [1.01-19.09]) and non-fetal indication of cesarean (OR=2.10[1.01-4.42]). The factors associated with post-partum morbidity were twin-pregnancy (OR=2.90 [1.12-7.54]), general anesthesia (OR=4.19 [1.68-10.49]) and non-cephalic fetal presentation (OR= 2.70 [1.23-5.93]).

CONCLUSION

The maternal morbidity of cesareans before 32 week of gestation is more than 20%. This study confirms the high maternal morbidity associated with caesareans performed before 32 weeks of gestation.

Labor induction in indicated moderate to late preterm birth

Introduction: The primary objective of this study was to evaluate the success of labor induction for indicated moderate and late preterm birth. As secondary objectives, the mode of delivery was assessed.Material and methods: This is an observational study conducted in a tertiary care unit between 2013 and 2015. All patients who underwent labor induction for indicated preterm birth between 32⁺⁰ and 36⁺⁶ weeks of gestation (as premature rupture of membranes, preeclampsia, intrauterine growth restriction, fetomaternal alloimmunization, or intrahepatic cholestasis) were included. The main outcome was the success of labor induction defined by repeated uterine contractions associated with cervical dilation >3 cm. The secondary outcomes were mode of delivery and neonatal outcomes.Results: Among 824 women who gave birth during the study period, 105 (12.7%) underwent induction of labor for indicated preterm birth. Labor induction was successful in 90.5% of cases (95/105), and 72.4% of the women (76/105) delivered vaginally. The success rate did not differ significantly in cases of moderate (32⁺⁰ to 33⁺⁶ weeks), compared with late (34⁺⁰ to 36⁺⁶ weeks) preterm birth (87.5 versus 90.7%, p = .56). The vaginal delivery rate was significantly lower in moderate compared to late preterm birth (37.5 versus 75.3%, p = .03).Conclusion: The success of labor induction and consecutive vaginal delivery were high in case of moderate and late preterm birth. Labor induction can be considered as an effective option for medical indications.