Induction of labour: clinical predictive factors for success and failure

Association of maternal Body Mass Index and parity on induced labor stages

BACKGROUND

Obesity is a widespread pandemic and obstetric care must adapt to meet the needs of obese pregnant women. Little is known about the impact of Body Mass Index (BMI) on the induction of labor (IOL). Therefore, our objective was to evaluate if the duration of the first and second stages of IOL is affected by maternal BMI in nulliparous and multiparous women.

METHODS

We included singleton pregnancies at term with cephalic presentation whose labor was induced from June 2018 to December 2019. Women were divided into two groups according to pre-pregnancy BMI in normal weight and obese women.

RESULTS

A total of 668 women with IOL were included in the study, among them, 349 had a normal weight and 321 were obese. The first stage of labor was longer in obese multiparous than normal-weight women (normal weight 81.98±71.7 vs. obese 134.3±158.1 min, P=0.000), while the second stage resulted significantly shorter (normal weight 22.2±27.8 vs. obese 14.3±14.2 min, P=0.000). The total time elapsed from IOL beginning and delivery was significantly higher in obese nulliparous (normal weight 10.4±19.7 vs. obese 22.0±26.2 h, P=0.000). Operative vaginal deliveries, emergency cesarean section, and failed IOL resulted to be similar between the groups.

CONCLUSIONS

Obese multiparous women have longer first stages of labor while shorter second stages. The total time for induced obese nulliparous to reach delivery is higher than the normal weight. It might be reasonable to reconsider the partographs according to maternal BMI in case of induced labor for future obstetric practice.

Failed induction of labor in term nulliparous women with an unfavorable cervix: Comparison of cervical ripening by two forms of vaginal prostaglandins (slow-release pessary and vaginal gel)

OBJECTIVE

To compare the rate of failed induction after cervical ripening by two forms of vaginal prostaglandins.

MATERIAL AND METHODS

This two-year retrospective study (January 1, 2016, through December 31, 2017) in two tertiary maternity units included nulliparous women with a singleton fetus in cephalic presentation and an unfavorable cervix requiring labor induction for prolonged pregnancy. The principal endpoint was the rate of failed induction, defined by the performance of a cesarean delivery before 6 cm of dilation. Cervical ripening was initiated by prostaglandins for 24 h, using a slow-release pessary (unit A) or a vaginal gel (unit B). The care protocol of the two groups after the first 24 h were similar. The women's individual characteristics were compared between the two units. The rates of failed induction were then compared between the two units, first by univariate and then by multivariable analysis adjusted for the characteristics that differed significantly between the units.

RESULTS

Among the 17,217 women delivered in the two maternity units during the study period, 178 met our inclusion criteria (125 in unit A (slow-release pessary) and 53 in unit B (vaginal gel)). The rate of failed induction was similar: 21.6% in unit A (slow-release pessary) and 17.0% in unit B (vaginal gel) (P = 0.48). The multivariate analysis did not show any difference about failed induction, time from the onset of induction to delivery, and vaginal delivery rate within 24h.

CONCLUSION

The rate of failed induction of labor did not differ between slow-release pessary and vaginal gel.

Predictive factors for vaginal delivery by induction of labor in uncomplicated pregnancies at 40-41 gestational weeks: A Japanese prospective single-center cohort study

AIM

We investigated cervical parameters predictive of vaginal delivery in elective labor induction among women at 40-41 gestational weeks.

METHODS

This Japanese prospective single-center cohort study was conducted between July 2019 and June 2020. We enrolled women with an uncomplicated singleton pregnancy who underwent labor induction at 40-41 gestational weeks. We analyzed background characteristics and cervical parameters, including Bishop score, cervical length, posterior cervical angle, and changes in cervical parameters before and after cervical dilatation. The endpoint was the rate of vaginal delivery.

RESULTS

Of 142 eligible participants, all 24 multiparous women underwent vaginal delivery. Among the nulliparous women (n = 118), the following categories showed significantly higher rates of vaginal delivery: Bishop scores of ≥6 before and after dilatation, compared with Bishop score <6 (adjusted prevalence ratio (aPR) [95% confidence interval (CI)]; 1.58 [1.17-2.13] and 1.56 [1.13-2.14], respectively) and cervical length of <10 and 10-20 mm before dilation, compared with cervical length of >30 mm (aPR [95% CI]; 1.47 [1.00-2.15] and 2.13 [1.42-3.18], respectively). The posterior cervical angle and other background characteristics showed no significant associations. Furthermore, women with cervical lengths of ≥20 mm before and <20 mm after dilatation showed a higher rate of vaginal delivery, compared to cervical length of ≥20 mm even after dilatation (aPR [95% CI]; 1.95 [1.19-3.20]).

CONCLUSIONS

High Bishop score, short cervical length, and changes in cervical length with dilatation are potential independent predictors of vaginal delivery following elective labor induction in nulliparous women at 40-41 gestational weeks.

Prognostic factors for successful induction of labor in intrauterine growth restriction after 36 weeks of gestation

OBJECTIVE

In comparison to eutrophic fetuses, intra uterine growth restriction fetuses (IUGR) have a higher risk of perinatal morbi-mortality. There are no guidelines on the labor induction of labor (IOL) method to be performed in IUGR. The main objective was to determine fetal and maternal predictive factors of successful induction in IUGR fetuses from 36 weeks. Study design We conducted a retrospective cohort single-center study including 320 women with a cephalic fetal presentation. Labour was induced after 36 weeks for suspected IUGR between January 2013 and December 2019.

RESULTS

Among the 320 patients, 246 were delivered vaginally (76.9 %) and 74 had a cesarean (23.1 %). Prognostic factors for successful IUGR induction were nonscarring uterus (OR 8.41; 95 %CI [2.92-24.21]), absence of preeclampsia (OR 7.14; 95 %CI [2.42-21.03]), multiparity (OR 4.32; 95 %CI [1.83-10.18]), normal fetal heart rate before IOL (OR 2.99; 95 %CI [1.24-7.22]) and BMI < 30 (OR 3.54; 95 %CI [1.62-7.72]). Doppler abnormalities, method and number of line of IOL, cervical evaluation were not significant in our study.

CONCLUSION

The prognostic factors for successful IUGR induction are essentially maternal. Thus, a low BMI, multiparity, nonscarring uterus, absence of preeclampsia, and a normal FHR are good prognostic factors in IUGR induction.

Retrospective Analysis of the Factors Affecting the Induction of Childbirth in 4350 Women from a Single Center in Warsaw, Poland

Labor induction is one of the most common procedures performed during childbirth, on average in 20−30% of all pregnant women. The aim of this paper was to perform a retrospective analysis of the factors influencing the induction of childbirth. The data provide population-based evidence for Poland (Masovian Voivodeship). The electronic patient records of a hospital in Warsaw were used to create an anonymous retrospective database of all deliveries from 2015 to 2020. The study included an analysis of two groups of patients. The study group consisted of patients with labor induction—4350 cases, and the control group of patients with spontaneous contractions—20,345. The factors influencing the lower frequency of labor induction in the study group were previous cesarean section (OR = 0.73, 95% CI: 0.64−0.84, p < 0.05) and a higher number of deliveries (OR = 0.74, 95% CI: 0.68−0.80, p < 0.05). It is necessary to conduct further research about obstetric procedures used during childbirth, such as induction of childbirth, to reduce the risk of complications and improve the perinatal care of the mother and the neonate.

Maternal and perinatal outcomes in women ≥40 years undergoing induction of labor compared with women <35 years: Results from 4027 mothers

AIM

Cesarean section is known to be increased with advanced maternal age in women undergoing induction of labor (IOL), but there is less information regarding other possible adverse maternal and fetal outcomes.

METHODS

Retrospective cohort study of singleton, nulliparous, at-term women undergoing IOL between January 2007 and September 2020. Outcomes studied were: cesarean section, failed induction rate, fetal distress, post-partum hemorrhage, post-partum hysterectomy, and need of transfusion. Neonatal variables analyzed were: Apgar score, umbilical cord pH, need of admission to neonatal intensive care unit, and mortality.

RESULTS

A total of 4027 women met the inclusion criteria; 1968 (48.9%) of mothers were <35 years, 1283 (31.9%) were 35-39 years, 658 (16.3%) were 40-44 years, and 118 (2.9%) were ≥45 years. Results showed a significantly increased incidence of c-section in women ≥35 years, with an OR 1.79 (95% CI 1.50-2.14) for women 40-44 years and OR 3.95 (95% CI 2.66-5.98) for women ≥45 years. The main indication for cesarean delivery was failed IOL, and this risk was also significantly increased in women ≥40 years. These differences remained significant after adjustment for confounding factors. No other adverse maternal or fetal outcomes showed an association with age.

CONCLUSION

Maternal age ≥40 years was associated with an increased risk of c-section after IOL at term compared with younger women, mainly because of failed induction, but no association with other adverse maternal or neonatal outcomes were found in our population. Risks and benefits of IOL in older women should be individually evaluated and adequately discussed with mothers.

Failed induction of labor and associated factors in Adama Hospital Medical College, Oromia Regional State, Ethiopia

Background:

Failed induction of labor continues to be a public health challenge throughout the world. This failed induction of labor is associated with a higher rate of maternal and fetal morbidity because it increases the unwanted effect of emergency cesarean section. It is also associated with an increased risk of numerous adverse maternal and perinatal outcomes such as uterine rupture, nonreassuring fetal heart rate tracing, postpartum hemorrhage, stillbirth, and severe birth asphyxia. Thus, this study was aimed to assess the failed induction of labor and associated factors in the Adama Hospital Medical College, Oromia Regional State, Ethiopia.

Methods:

A facility-based cross-sectional study was conducted from 1 to 30 December 2020 in Adama Hospital Medical College, Ethiopia. A total of 379 women who underwent labor induction in the Adama Hospital Medical College from December 2019 to November 2020 were enrolled in the study. The participants’ charts were selected using a simple random sampling technique. Data were collected using a pretested and validated structured questionnaire. Descriptive statistics were carried out using frequency tables, proportions, and summary measures. Predictors were assessed using a multivariable logistic regression analysis model and reported using adjusted odds ratio with 95% confidence interval. Statistical significance was considered at a p value <0.05.

Results:

Of 379 induced labor included in the study, the proportion of failed induction was found to be 29.6% (95% confidence interval (25.2, 34.3)). Prelabor rupture of the membrane was found to be the most common indication for induction of labor (46.4%) followed by a hypertensive disorder of pregnancy (21.6%). In the final model of multivariable analysis, predictors such as: nulliparity (adjusted odds ratio = 2.32, 95% confidence interval (1.08, 5.02)), unfavorable cervical status (adjusted odds ratio = 3.46, 95% confidence interval (1.51, 7.94)), prelabor rupture of membrane (adjusted odds ratio = 2.60, 95% confidence interval (1.14, 5.91)), hypertensive disorder of pregnancy (adjusted odds ratio = 3.01;95% confidence interval (1.61, 558)), preinduction membrane status (adjusted odds ratio = 3.63; 95% confidence interval (1.48, 8.86)), and birth weight of greater than 4000 g (adjusted odds ratio = 4.33; 95% confidence interval (1.44, 13.02)) were statistically associated with failed induction of labor.

Conclusion:

The prevalence of failed induction of labor was relatively high in this study area because more than a quarter of mothers who underwent induction of labor had failed induction. This calls for all stakeholders to adhere to locally available induction protocols and guidelines. In addition, pre-induction conditions must be a top priority to improve the outcome of induction of labor.

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.

Outcome of induction and associated factors among induced labours in public Hospitals of Harari Regional State, Eastern Ethiopia: A two years' retrospective analysis

Background

Induction of labor (IOL) is an essential intervention to reduce adverse maternal and neonatal outcomes. It is also improved pregnancy outcomes, especially in resource-limited countries, where maternal and perinatal mortality is unacceptably high. However, there is a scarcity of evidence regarding the outcome of induction of labor and its predictors in low-income countries like Sub-Saharan Africa. Therefore, this study was aimed at assessing the outcome of induction of labor and associated factors among mothers who underwent labor induction in public Hospitals of Harari Regional State, Estern Ethiopia.

Methods

A facility-based cross-sectional study was conducted from 1 to 30 March, 2019 in Harari Regional State, Eastern Ethiopia. A total of 717 mothers who underwent induction of labor in public Hospitals of Harari Regional State, Eastern Ethiopia from January 2017 to December 2018 were enrolled in the study. Data were collected using a pretested structured questionnaire. The collected data were entered into Epi-data version 3.1 and exported to SPSS version 24 (IBM SPSS Statistics, 2016) for further analysis. A multivariable logistic regression analysis was performed to estimate the effects of each predictor variable on the outcome of induction of labor after controlling for potential confounders. Statistical significance was declared at p-value <0.05.

Results

Overall, the prevalence of success of induction of labor was 65% [95% CI (61.5, 68.5)]. Pre-eclampsia/eclampsia was found to be the most common indication for induction of labor (46.70%) followed by pre-labor rupture of fetal membrane (33.5%). In the final model of multivariable analysis, predictors such as: maternal age < 24 years old [AOR = 1.93, 95%CI(1.14, 3.26)], nulliparity[AOR = 0.34, 95%CI(0.19, 0.59)], unfavorable Bishop score [AOR = 0.06, 95%CI(0.03, 0.12)], intermediate Bishop score [AOR = 0.08, 95%CI(0.04, 0.14)], misoprostol only method [AOR = 2.29, 95%CI(1.01, 5.19)], nonreassuring fetal heart beat pattern [AOR = 0.14, 95%CI (0.07, 0.25)] and Birth weight 3500 grams and above[AOR = 0.32, 95% CI (0.17, 0.59)] were statistically associated with the successful outcome of induction of labor.

Conclusion

The prevalence of successful of induction of labor was relatively low in this study area because only two-thirds of the mothers who underwent induction of labor had a successful of induction. Therefore, this result calls for all stakeholders to give more emphasis on locally available induction protocols and guidelines. In addition, pre-induction conditions must be taken into consideration to avoid unwanted effect of failed induction of labour.

Clinical predictive factors for vaginal delivery following induction of labour among pregnant women in Jordan

Background

Induction of labour (IOL) is an important and common clinical procedure in obstetrics. In the current study, we evaluate predictors of vaginal delivery in both nulliparous and multiparous women in north Jordan who were induced with vaginal prostaglandins.

Method

A prospective study was conducted on 530 pregnant women at King Abdullah University Hospital (KAUH) in north Jordan. All pregnant mothers with singleton live fetuses, who had induction of labour (IOL) between July 2017 and June 2019, were included in the study. Mode of delivery, whether vaginal or caesarean, was the primary outcome. Several maternal and fetal variables were investigated. The safety and benefit of repeated dosage of vaginal prostaglandin E2 (PGE2) tablets, neonatal outcomes and factors that affect duration of labour were also evaluated.

Pearson χ2 test was used to investigate the significance of association between categorical variables, while student’s t-test and ANOVA were applied to examine the mean differences between categorical and numerical variables. Linear regression analysis was utilized to study the relation between two continuous variables. A multivariate regression analysis was then performed. Significance level was considered at alpha less than 0.05.

Results

Nulliparous women (N = 254) had significantly higher cesarean delivery rate (58.7% vs. 17.8%, p < 0.001) and longer duration of labour (16.1 ± 0.74 h vs. 11.0 ± 0.43 h, p < 0.001) than multiparous women (N = 276). In nulliparous women, the rate of vaginal delivery was significantly higher in women with higher Bishop score; the mean Bishop score was 3.47 ± 0.12 in nulliparous women who had vaginal delivery vs. 3.06 ± 0.10 in women who had cesarean delivery (Adjusted odds ratio (AOR) = 1.2, 95% CI: 1.03–1.28, p = 0.03). In multiparous women, the rate of vaginal delivery was significantly higher in women with higher Bishop scores and lower in women with higher body mass index (BMI). The mean Bishop score was 3.97 ± 0.07 in multiparous women who had vaginal delivery vs. 3.56 ± 0.16 in women who had cesarean delivery (AOR = 1.5, 95% CI: 1.1–2.1, p = 0.01). The mean BMI was 30.24 ± 0.28 kg/m² in multiparous women who had vaginal delivery vs. 32.36 ± 0.73 kg/m² in women who had cesarean delivery (AOR = 0.89, 95% CI: 0.84–0.96, p = 0.005). 27% of nulliparous women who received more than two PGE2 tablets and 50% of multiparous women who received more than two PGE2 tablets had vaginal delivery with no significant increase in neonatal morbidity.

Conclusion

Parity and cervical status are the main predictors of successful labour induction. Further studies are required to investigate the benefit of the use of additional doses of vaginal PGE2 above the recommended dose for IOL.

Towards an evidence-based approach to optimize the success of labour induction

Induction of labour is a two-step process involving cervical ripening and the initiation of uterine contractions, with the goal of achieving vaginal birth. To optimize the chance of a safe and timely vaginal birth, the process of induction of labour should be evidence based and individualized to the given person and situation. In this study, we lay out a framework for how this should be done, emphasizing on careful clinical assessment and planning, flexibility in the strategy of induction, patience during the ripening and latent phases of labour, and thoughtful consideration regarding changing the strategy if active labour is not initially achieved. The goal of this review is to present the current evidence on this topic in the form of a user-friendly protocol that can be easily adapted to institutional practice.

Predicting factors of failed induction of labor in three hospitals of Southwest Ethiopia: a cross-sectional study

Introduction

Failed induction of labor affects maternal and neonatal outcomes as well as the cost of healthcare, especially in low-resource setting regions in which the prevalence of failed induction is higher despite the incidence of labor induction is low. This study aimed to assess the prevalence of failed induction of labor in southwest Ethiopia.

Method

A hospital-based cross-sectional study was conducted among 441 induced women from March 1 to August 30, 2018. A systematic random sampling technique was used to select study participants. Data were collected using a pretested and structured questionnaire. Bivariable and multivariable logistic regression models were done and fitted to identify predictors of failed induction. An adjusted odds ratio with 95% confidence interval (CI) was calculated to determine the level of significance.

Result

Premature rupture of membrane was the most common cause of labor induction and the commonly used method of labor induction were oxytocin infusion. Cesarean section was done for 28.1% of induced women. Failed induction of labor was found to be 21%. Primiparous [AOR = 2.35 (1.35–4.09)], analgesia/anesthesia [AOR = 4.37 (1.31–14.59)], poor Bishop Score [AOR = 2.37 (1.16–4.84)], Birth weight ≥ 4 k grams [AOR = 2.12 (1.05–4.28)] and body mass index [AOR = 5.71 (3.26–10.01)] were found to be significantly associated with failed induction of labor.

Conclusion

The prevalence of failed induction of labour was found to be high. Preparation of the cervix before induction in primi-parity women is suggested to improve the success of induction. To achieve the normal weight of women and newborns, proper nutritional interventions should be given for women of reproductive age. It is better to use analgesia/anesthesia for labor induction when it becomes mandatory and there are no other optional methods of no- pharmacologic pain management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03862-x.

The degree of cervical length shortening as a predictor of successful or failed labor induction

OBJECTIVE

To evaluate whether the degree of cervical length change was associated with successful cervical dilatation during labor induction.

MATERIALS AND METHODS

We conducted a secondary analysis of a prospective observational study of term singleton pregnant women who underwent labor inductions. Cases of Cesarean section due to fetal distress or maternal request during the first stage of labor were excluded. The enrolled women were categorized into two groups according to achievement of full cervical dilatation. The cervical length near induction and cervical length shortening over the last four weeks of pregnancy were compared between the two groups. A receiver operating characteristics (ROC) analysis was performed to evaluate the screening performance for failed cervical dilatation during labor induction.

RESULTS

A total of 165 women were enrolled for the final analysis; of these, 145 (87.9%) women reached the second stage of labor and 20 (12.1%) women failed to achieve full cervical dilatation. Women who failed to achieve full cervical dilatation had a significantly longer cervical length near induction and less cervical length change over previous four weeks compared with women who achieved full cervical dilatation (P = 0.018 and 0.005, respectively). Multivariate analysis showed that cervical length >29 mm (odds ratios [OR], 4.15; 95% confidence interval [CI], 1.290-13.374, P = 0.017) and cervical length shortening ≦ 6 mm (OR, 5.87; 95% CI, 1.552-22.271, P = 0.009) were significantly associated with failed cervical dilatation after adjusting for birthweight and previous history of vaginal delivery. Cervical length shortening alone provided a better prediction of failed cervical dilatation than the combination of cervical length and shortening (sensitivity, 76.9%; specificity, 63.8%).

CONCLUSION

The probability of failed cervical dilatation during labor induction was significantly increased in cases when the cervical length was greater than 29 mm near induction or when the cervical length shortening was less than 6 mm over the last four weeks.

Predictor variables in the success of slow-release dinoprostone used for cervical ripening in intrauterine growth restriction pregnancies

OBJECTIVE

This study aims to evaluate the consequences of a trigger by vaginal Dinoprotone on outcome of pregnancies with Intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

This retrospective study included 161 induced IUGR fetuses (35-39 weeks). Consecutive patients who were evaluated formed the basis of the clinical outcomes. The penalized maximum likelihood estimation (PMLE) method was used instead of traditional logistic regression in order to reduce the risk of overfitting.

RESULTS

Of the 25,678 deliveries that occurred during the study period, 161 (0.6%) women underwent IUGR delivery; of these, 117 (73%) succeeded and 44 (27%) failed to achieve cervical ripening using the dinoprostone slow-release vaginal insert. Two predictors were associated with dinoprostone vaginal delivery success: Parity (OR:1.4([0.89-2.3]), and Bishop score (OR:1.54[1.23-1.94]). The PMLE model correctly classified 78% participants (c-index: 0.78).

CONCLUSION

Basic parameters such as parity and Bishop score can be used to predict successful vaginal birth following dinoprostone slow-release vaginal insert administration.

Metabolic Pathways Associated With Term Labor Induction Course in African American Women

OBJECTIVES

The purpose of this study was to evaluate differences in the metabolic pathways activated in late-pregnancy serum samples among African American women who went on to have term (≥37 weeks) labor induction requiring high total oxytocin doses to complete first-stage labor compared to those in similar women with low-oxytocin labor inductions.

STUDY DESIGN

Case-control study (N = 27 women with labor induction with successful cervical ripening: 13 requiring the highest total doses of synthetic oxytocin to progress from 4- to 10-cm cervical dilation and 14 requiring the lowest total doses) with groups balanced on parity and gestational age. Serum samples obtained between 24 and 30 weeks' gestation were analyzed using ultra-high-resolution metabolomics. Differentially expressed metabolites between high-oxytocin induction cases and low-oxytocin induction comparison subjects were evaluated using linear regression with xmsPANDA. Metabolic pathways analysis was conducted using Mummichog Version 2.0, with discriminating metabolites annotated using xMSannotator Version 1.3.

RESULTS

Labor processes were similar by group with the exception that cases received over 6 times more oxytocin between 4- and 10-cm cervical dilation than comparison women. Induction requiring high total doses of synthetic oxytocin was associated with late-pregnancy serum levels of metabolites from the linoleate and fatty acid activation pathways in term, African American women.

CONCLUSION

Serum levels of several lipid metabolites predicted more complicated labor induction involving higher doses of synthetic oxytocin to complete first-stage labor. Further investigation in larger, more diverse cohorts of women is needed to identify potential targets to prevent failed labor induction.

Influence of maternal age in mode of delivery after term induction of labor

Objective: To determine the impact of maternal age on the rate of cesarean delivery in women undergoing induction at term.Study Design: Retrospective cohort study of term singleton gestations in nulliparous women induced for any indication at Lehigh Valley Health Network from July 2010 to July 2013. Exposure of interest was maternal age. Primary outcome was cesarean delivery. For every one woman ≥35 years of age (exposed), 2-3 women <35 years of age were selected as unexposed subjects for comparison. Statistical analysis included bivariate and multivariable techniques.Results: 406 patients were included; 101 women ≥35 years of age and 305 women <35 years of age. Women in the ≥35 group were more likely to be induced for maternal medical conditions and less likely to be induced for prolonged pregnancy; few inductions were elective. Few women were induced electively in either group. More than half of women in both groups required cervical ripening. Method of cervical ripening and/or induction and percentage of women with a Bishop score <5 were similar between groups. The primary outcome, cesarean delivery, was similar between groups (45.5% in age ≥35 group vs 40.0% in age <35 group, p = .33). After adjustment for potential confounders, the rate of cesarean delivery was not influenced by maternal age (AOR 1.21 [0.76, 1.91], p = .42) but was higher in women with a Bishop score <5 at the time of induction of labor [AOR 1.64 [1.09, 2.47], p = .02].Conclusion: In the wake of several recent trials underscoring the safety and potential maternal and fetal benefit of labor induction, identifying predictors of induction success (and failure) takes on increasing importance. Our findings suggest that maternal age is not an independent risk factor for cesarean delivery in women undergoing induction.

Recent advances in the induction of labor

The rate of labor induction is steadily increasing and, in industrialized countries, approximately one out of four pregnant women has their labor induced. Induction of labor should be considered when the benefits of prompt vaginal delivery outweigh the maternal and/or fetal risks of waiting for the spontaneous onset of labor. However, this procedure is not free of risks, which include an increase in operative vaginal or caesarean delivery and excessive uterine activity with risk of fetal heart rate abnormalities. A search for “Induction of Labor” retrieves more than 18,000 citations from 1844 to the present day. The aim of this review is to summarize the controversies concerning the indications, the methods, and the tools for evaluating the success of the procedure, with an emphasis on the scientific evidence behind each.