Incidence of and Risk Factors for Failed Induction of Labor Using a Contemporary Definition

Evidence-Based Approaches to Labor Induction

Importance

The induction rate continues to increase in the United States placing pressure on the health care system with increasing cost and time spent on labor and delivery. Most labor induction regimens have evaluated uncomplicated singleton-term gestations. Unfortunately, the optimal labor regimens of medically complicated pregnancies have not been well described.

Objective

The aim of this study was to review the current available evidence regarding the various labor induction regimens and understand the evidence that exists for induction regimens in complicated pregnancies.

Evidence Acquisition

Data were acquired by a literature search on PubMed, ClinicalTrials.gov, the Cochrane Review database, the most recent American College of Obstetricians and Gynecologists practice bulletin on labor induction, and a review of the most recent edition on widely used obstetric texts for key words related to labor induction.

Results

Many heterogeneous clinical trials exist examining various labor induction regimens such as prostaglandin only, oxytocin only, or a combination of mechanical dilation with prostaglandins or oxytocin. Several Cochrane systematic reviews have been performed, which suggest a combination of prostaglandins and mechanical dilation results in an improved time to delivery when compared with single-use methods. Evaluating pregnancies complicated by maternal or fetal conditions, there exist retrospective cohorts describing significantly different labor outcomes. Although a few of these populations have planned or active clinical trials, most do not have an optimal labor induction regimen described.

Conclusions and Relevance

Most induction trials are significantly heterogeneous and limited to uncomplicated pregnancies. A combination of prostaglandins and mechanical dilation may result in improved outcomes. Complicated pregnancies have significantly different labor outcomes; however, almost none have well-described labor induction regimens.

Factors Influencing the Duration of Termination of Pregnancy for Fetal Anomaly with Mifepristone in Combination with Misoprostol

This study's aim was to determine relevant factors that influence the time interval between first induction and fetal expulsion in late termination of pregnancy (TOP) and TOP after previous feticide for severe fetal malformation with a mifepristone-misoprostol regime. This retrospective study included 913 TOPs from a single tertiary care referral center. In 197 out of 913 TOPs, a previous feticide had been performed due to advanced gestational age (after 22 + 0 weeks of gestation). Induction was accomplished using 600 mg mifepristone followed by 400 μg misoprostol. The interval between first induction with misoprostol and fetal expulsion was examined. Univariate and multivariate logistic regression analysis were used to predict an induction interval of 12 h or less. The median gestational age at induction of labor was 18.9 weeks of pregnancy. In 487 (53.3%) cases women delivered within 12 h; in 344 (37.7%) cases the induction interval was between 12 h and 36 h. In 82 (9%) cases induction took longer than 36 h. Factors that were significantly associated with a delivery duration of <12 h were a lower gestational age at induction (OR 0.87; 95% CI 0.84-0.89; p < 0.001) and a history of at least one previous vaginal delivery (OR 1.57; 95% CI 1.20-2.05; p < 0.001). Factors that had no impact included previous cesarean section, performing feticide before induction and maternal age. Maternal BMI showed a non-significant trend.

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.

Maternal and Neonatal Outcomes of Elective Induction of Labor at 39 or More Weeks: A Prospective, Observational Study

The purpose of our study is to compare the maternal and neonatal outcomes of induction of labor (IOL) versus expectant management at 39 weeks of gestation. We conducted a single-centered, prospective, observational study of nulliparous singleton women at 39 weeks or more. We compared the maternal and perinatal outcomes. Of 408 nulliparous women, 132 women were IOL group and 276 women were expectant management group. IOL and expectant group had similar cesarean delivery rate (18.2% vs. 15.9%, p = 0.570). The delivery time from admission was longer in IOL group (834 ± 527 vs. 717 ± 469 min, p = 0.040). The IOL group was less likely to have Apgar score at 5 min < 7 than in expectant group (0.8% vs. 5.4%, p = 0.023). Multivariate analysis showed that IOL at 39 weeks was not an independent risk factor for cesarean delivery (relative risk 0.64, 95% confidence interval: 0.28−1.45, p = 0.280). Maternal and neonatal adverse outcomes, including cesarean delivery rate, were similar to women in IOL at 39 weeks of gestation compared to expectant management in nulliparous women. IOL at 39 weeks of gestation could be recommended even when the indication of IOL is not definite.

Comparison of transvaginal sonographic cervical length measurement and Bishop score for predicting labour induction outcomes

OBJECTIVES

Induction of labour (IOL) is of increasing prevalence worldwide and reliable prediction of its successful outcome is important. Traditional clinical methods for predicting successful IOL outcomes have been supplemented with newer technologies. The aim of this study was to compare transvaginal sonographic (TVS) cervical length measurement with Bishop score in predicting labour induction outcomes.

METHODS

This study included pregnant women with term pregnancy, indication for IOL and unfavourable cervix (Bishop score >6) who had TVS performed prior to IOL. Exclusion critetia were regular contractions, ruptured membranes, non-cephalic presentation, uterine scar and pregnancy complications potentially influencing study outcomes. Outcomes measured were successful IOL defined as achievement of active phase of labour and vaginal delivery. Receiver operating characteristic (ROC) curves were used to determine diagnostic accuracy and sensitivity, specificity, positive and negative predictive values. Statistical significance was defined as p<0.05.

RESULTS

Among 112 studied participants, IOL was successful in 101 (90.2%) pregnant women. AUC for Bishop score >2 was 0.831 (95% CI, 0.744-0.917, p<0.001) and for cervical length <30 mm 0.679 (95% CI 0.514-0.844, p<0.052). A total of 81 (72.3%) pregnant women delivered vaginally; AUC for Bishop score >2 was 0.754 (95% CI 0.648-0.861, p<0.001) and for cervical length <30 mm 0.602 (95% CI 0.484-0.720, p=0.092) which was the only insignificant predictor.

CONCLUSIONS

Bishop score >2 is a better predictor for both successful IOL and vaginal delivery among induced women with term pregnancy and unfavourable cervix compared to cervical length <30 mm.

Establishment of a model for predicting the outcome of induced labor in full-term pregnancy based on machine learning algorithm

To evaluate and establish a prediction model of the outcome of induced labor based on machine learning algorithm. This was a cross-sectional design. The subjects were divided into primipara and multipara, and the risk factors for the outcomes of induced labor were assessed by multifactor logistic regression analysis. The outcome model of labor induced with oxytocin (OT) was constructed based on the four machine learning algorithms, including AdaBoost, logistic regression, naive Bayes classifier, and support vector machine. Factors, such as accuracy, recall, precision, F1 value, and receiver operating characteristic curve, were used to evaluate the prediction performance of the model, and the clinical application of the model was verified. A total of 907 participants were included in this study. Logistic regression algorithm obtained better results in both primipara and multipara groups compared to the other three models. The accuracy of the model for the prediction of "successful induction of labor" was 94.24% and 96.55%, and that of "failed induction of labor" was 65.00% and 66.67% in the primipara and the multipara groups, respectively. This study established a prediction model of OT-induced labor based on the Logistic regression algorithm, with rapid response, high accuracy, and strong extrapolation, which was critical for obstetric clinical nursing.

A Peripheral Immune Signature of Labor Induction

Approximately 1 in 4 pregnant women in the United States undergo labor induction. The onset and establishment of labor, particularly induced labor, is a complex and dynamic process influenced by multiple endocrine, inflammatory, and mechanical factors as well as obstetric and pharmacological interventions. The duration from labor induction to the onset of active labor remains unpredictable. Moreover, prolonged labor is associated with severe complications for the mother and her offspring, most importantly chorioamnionitis, uterine atony, and postpartum hemorrhage. While maternal immune system adaptations that are critical for the maintenance of a healthy pregnancy have been previously characterized, the role of the immune system during the establishment of labor is poorly understood. Understanding maternal immune adaptations during labor initiation can have important ramifications for predicting successful labor induction and labor complications in both induced and spontaneous types of labor. The aim of this study was to characterize labor-associated maternal immune system dynamics from labor induction to the start of active labor. Serial blood samples from fifteen participants were collected immediately prior to labor induction (baseline) and during the latent phase until the start of active labor. Using high-dimensional mass cytometry, a total of 1,059 single-cell immune features were extracted from each sample. A multivariate machine-learning method was employed to characterize the dynamic changes of the maternal immune system after labor induction until the establishment of active labor. A cross-validated linear sparse regression model (least absolute shrinkage and selection operator, LASSO) predicted the minutes since induction of labor with high accuracy (R = 0.86, p = 6.7e-15, RMSE = 277 min). Immune features most informative for the model included STAT5 signaling in central memory CD8⁺ T cells and pro-inflammatory STAT3 signaling responses across multiple adaptive and innate immune cell subsets. Our study reports a peripheral immune signature of labor induction, and provides important insights into biological mechanisms that may ultimately predict labor induction success as well as complications, thereby facilitating clinical decision-making to improve maternal and fetal well-being.

Induction of labour in low-resource settings

Due to the disparity in resource availability between low- and high-resource settings, practice recommendations relevant to high-income countries are not always relevant and often need to be adapted to low-resource settings. The adaptation applies to induction of labour (IOL) which is an obstetric procedure that deserves special attention because it involves the initiation of a process that requires regular and frequent monitoring of the mother and foetus by experienced healthcare professionals. Lack of problem recognition and/or substandard care during IOL may result in harm with long-term sequelae. In this article, the authors discuss unique challenges such as insufficient resources (including staff, midwives, doctors, equipment, and medications) that result in occasional inadequate patient monitoring and/or delayed interventions during IOL in low-resource settings. We also discuss modifications in indications and methods for IOL, issues related to human immunodeficiency virus (HIV) infections, the feasibility of outpatient induction, clinical protocols and a minimum dataset for quality improvement projects. Overall, the desire to achieve a vaginal birth with IOL should not cloud the necessity to observe the required safety measures and implement necessary interventions; given that childbirth practices are the major determinants of pregnancy outcomes and patient satisfaction.

Review of Evidence-Based Methods for Successful Labor Induction

Induction of labor is increasingly a common component of the intrapartum care. Knowledge of the current evidence on methods of labor induction is an essential component of shared decision-making to determine which induction method meets an individual's health needs and personal preferences. This article provides a review of the current research evidence on labor induction methods, including cervical ripening techniques, and contraction stimulation techniques. Current evidence about expected duration of labor following induction, use of the Bishop score to guide induction, and guidance on the use of combination methods for labor induction are reviewed.