Predictors of successful labor induction with oral or vaginal misoprostol

The Relationship between Gestational Weight Gain and Cesarean Delivery among Patients undergoing Induction of Labor

OBJECTIVE

 This study aimed to determine the impact of pregnancy weight gain above National Academy of Medicine (NAM) guidelines on cesarean delivery rates following induction.

STUDY DESIGN

 This is a secondary analysis of a prospective cohort study of patients who underwent induction at a single tertiary care center between July 2017 and July 2019. Included in the primary study were patients undergoing term (≥37 weeks) labor induction with a singleton gestation, intact membranes, and unfavorable cervical examination (Bishop score of ≤6 and cervical dilation ≤ 2 cm). Eligibility for this analysis was limited to patients with a documented prenatal body mass index (BMI) < 20 weeks' gestation. The primary exposure was gestational weight gain greater than NAM guidelines (WGGG) for a patient's initial BMI category. The primary outcome was cesarean delivery for any indication.

RESULTS

 Of 1,610 patients included in the original cohort, 1,174 (72.9%) met inclusion criteria for this analysis and 517 (44.0%) of these had weight gain above NAM guidelines. Of the entire cohort, 60.0% were Black and 52.7% had private insurance. In total, 160 patients (31%) with WGGG underwent cesarean compared with 127 patients (19.3%) without WGGG (p < 0.001), which equates to a 59% increased odds of cesarean when controlling for initial BMI category, parity, gestational diabetes, and indication for induction (Adjusted Odds Ratio [aOR] 1.58, 95% confidence interval [CI] 1.17-2.12). Among only nulliparous patients, WGGG was associated with an increased odds of cesarean (26.4 vs. 38.2%, aOR 1.50, 95% CI 1.07-2.10). In multiparous patients, however, there was no difference in cesarean between those with and without WGGG (8.8 vs. 14.1%, aOR 1.85, 95% CI 0.96-3.58).

CONCLUSION

 This study demonstrates that weight gain above NAM guidelines is associated with more than a 50% increased odds of cesarean. Patients should be informed of this association as gestational weight gain may be a modifiable risk factor for cesarean delivery.

KEY POINTS

· Weight gain above NAM guidelines was associated with a 59% increased odds of cesarean delivery.. · Nulliparous patients with weight gain above NAM guidelines are at higher risk of cesarean delivery.. · No difference in cesarean delivery among multiparous patients regardless of gestational weight gain..

Nomogram predicting cesarean delivery undergoing induction of labor among high-risk nulliparous women at term: a retrospective study

Background

Our aim was to create and validate a nomogram predicting cesarean delivery after induction of labor among nulliparous women at term.

Methods

Data were obtained from medical records from Nanjing Drum Tower Hospital. Nulliparous women with singleton pregnancies undergoing induction of labor at term were involved. A total of 2950 patients from Jan. 2014 to Dec. 2015 were served as derivation cohort. A nomogram was constructed by multivariate logistic regression using maternal, fetal and pregnancy characteristics. The predictive accuracy and discriminative ability of the nomogram were internal validated by 1000-bootstrap resampling, followed by external validation of a new dataset from Jan. 2016 to Dec. 2016.

Results

Logistic regression revealed nine predictors of cesarean delivery, including maternal height, age, uterine height, abdominal circumference, estimated fetal weight, indications for induction of labor, initial cervical consistency, cervical effacement and station. Nomogram was well calibrated and had an AUC of 0.73 (95% confidence interval [CI], 0.70-0.75) after bootstrap resampling for internal validation. The AUC in external validation reached 0.67, which was significantly higher than that of three models published previously (P<0.05).

Conclusions

This validated nomogram, constructed by variables that were obtained form medical records, can help estimate risk of cesarean delivery before induction of labor.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04386-8.

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.

Factors associated with delayed onset of active labor following vaginal misoprostol administration among women at Mbarara Regional Referral Hospital, Uganda

OBJECTIVE

To determine the factors associated with delayed onset of active labor following labor induction with vaginal misoprostol.

METHODS

We conducted a prospective cohort study over 6 months at a tertiary hospital in Uganda. We enrolled mothers with pregnancies of at least 28 weeks, who were undergoing labor induction with 50 µg of vaginal misoprostol, administered every 6 hours with a maximum of four doses, and followed them up until onset of active labor. Labor onset was considered delayed if it occurred later than 12 hours after the first dose. Bivariate and multivariate analysis was performed to determine factors associated with delayed onset of active labor.

RESULTS

Of the 88 mothers enrolled, 22.7% (n=20) had delayed onset of active labor. Nulliparity (adjusted relative risk [aRR] 2.34, 95% confidence interval [CI] 1.17-4.68) and gestational age less than 37 weeks (aRR 3.79, 95% CI 1.40-10.23) were associated with delayed onset of active labor following vaginal misoprostol administration whereas higher body mass index (aRR 0.38, 95% CI 0.18-0.79) decreased the risk.

CONCLUSION

Delayed onset of active labor following labor induction remains an important obstetric care challenge. Mothers undergoing labor induction should have their body mass index documented, and nulliparous women and mothers at less than 37 weeks of gestation should have their labor monitored for a longer duration following labor induction.

Predictors of response after a second attempt of pharmacological labor induction: a retrospective study

PURPOSE

The aim of our study was to assess the outcomes of a prolonged induction carried out with a second sequential cycle of pharmacological stimulation after unsatisfactory response to a first attempt, and to highlight variables correlated with higher response rates.

METHODS

A retrospective study was carried out on 157 women who underwent a two-step labor induction by vaginal prostaglandins followed by a second cycle of prostaglandins or intravenous oxytocin. Outcomes assessed were mode of delivery and maternal and neonatal morbidity. Main variables of pregnancy and delivery were collected to identify factors predicting the mode of delivery.

RESULTS

Among 157 patients, 63 (40.1%) achieved a vaginal delivery, whereas 94 (59.9%) underwent Cesarean section, 9 women (5.7%) had postpartum hemorrhage; in 2 cases (1.3%), an Apgar score < 7 at 5 min from birth was reported. Higher risk of Cesarean section was observed with advanced maternal age (OR 1.13 for additional year, CI 1.04-1.22) and nulliparity (OR 8.84, CI 2.69-29.06), whereas the response rates were better in carriers of group B streptococcus colonization (OR 0.38, CI 0.17-0.84) and in women with favorable cervical status after the first stimulation (OR 0.81 for additional point of Bishop score, CI 0.70-0.94).

CONCLUSION

Labor induction with two cycles of pharmacological stimulation is a procedure with fairly good success rates and a low risk of maternal and neonatal complications. Factors predicting its success encompass younger age, parity, a positive recto-vaginal swab for group B streptococcus and a favorable cervix following the first cycle of stimulation.

A comparison of misoprostol vaginal insert and misoprostol vaginal tablets for induction of labor in nulliparous women: a retrospective cohort study

Background

Since Misoprostol Vaginal Insert (MVI - Misodel ®) was approved for labor induction in Europe in 2013, to date, no study has been published comparing MVI to Misoprostol vaginal tablets (MVT). The aim of this study, performed as part of a quality improvement project, was to compare the efficacy and safety of 200 μg MVI versus 25 μg MVT for labor induction in nulliparous women.

Methods

This retrospective cohort study included 171 nulliparous singleton term deliveries induced with MVI (n = 85) versus MVT (n = 86) at Oslo University Hospital Rikshospitalet, Norway, from November 2014 to December 2015. Primary outcomes were time from drug administration to delivery in hours and minutes and the rate of cesarean section (CS). Results were adjusted for Bishop Score and pre-induction with balloon catheter.

Results

Median time from drug administration to delivery was shorter in the MVI group compared to the MVT group (15 h 43 min versus 19 h 37 min, p = 0.011). Adjusted for confounding factors, mean difference was 6 h 3 min (p = 0.002). The risk of CS was 67% lower in the MVI group compared to the MVT group (11.8% versus 23.3%, OR = 0.33; adjusted 95% CI 0.13–0.81). Adverse neonatal outcomes did not differ between the groups.

Conclusions

In a setting of routine obstetric care, MVI seems to be a more efficient labor induction agent than MVT, and with a lower CS rate and no increase in adverse infant outcomes.

Induction of labour: clinical predictive factors for success and failure

Induction of labour (IOL) is a widely-used practice in obstetrics. Our aim was to evaluate predictors of vaginal delivery in postdate pregnancies induced with prostaglandins. We conducted a retrospective cross-sectional study with analytic component. A total of 145 women, admitted for IOL after the 41st week of gestation, were induced with a vaginal pessary releasing prostaglandins. Type of delivery, whether vaginal or caesarean, was the outcome. Several maternal and foetal variables were investigated. The Kaplan-Maier curves, monovariate and a multivariate logistic regression were carried out. In our population, 80.7% of women had vaginal delivery after the induction. Multiparity and a high Bishop score at the beginning of the IOL were protective factors for a vaginal delivery (respectively OR 0.16, p = .028 and OR 0.62, p = .034) while age >35 years, and the foetal birth weight >3500 g at the birth, resulted in being risk factors for caesarean section (respectively OR 4.20, p = .006 and OR 3.63, p = .013). IMPACT STATEMENT What is already known on this subject: Induction of labour (IOL) is a widely used practice in obstetrics. Scientific literature shows several predictors of successful induction, although there is no unanimity except for 'multiparity' and 'favourable Bishop score' which are associated with positive outcome of the induction. The main difficulty in finding other predictive factors is the heterogeneity of this field (different local protocols in each hospital, type of induction, populations and outcomes chosen in each study). In addition to that, populations are not always comparable due to the different gestation. For this reason, we decided to select a specific population of women, such as low risk postterm pregnancies induced with prostaglandins, in order to detect possible predictive factors for the success of the IOL for women with uncomplicated pregnancies. What the results of this study add: Our study agrees with existing literature that 'multiparity' and 'Bishop score' are linked with the success of IOL and adds that 'maternal age' and 'foetal birth weight' are significant risk factors for the population of uncomplicated post term pregnancies induced with prostaglandins. What the implications are of these findings for clinical practice and/or further research: Our results agreed with the existing literature regarding parity and Bishop score but not for maternal age and birth weight. This adds new precious data to the literature which could be used for systematic reviews and for implementing IOL guidelines and protocols, nationally and internationally. Our findings could be also used for guiding future research in this field. It will be interesting to investigate the existence of not just specific factors but also any combination of variables which could predict the success of the procedure. At the moment these information cannot be used in terms of decision making for healthcare professionals as no variable is 100% predictive but once further research will be added, we may be able to know when is best time to start the IOL, how to facilitate the success of the procedure and how to best support the woman throughout the whole experience.

Induction of labor in elderly nulliparous women

PURPOSE

Maternal age is an important consideration for antenatal care, labor and delivery. We aimed to evaluate the induction of labor (IoL) failure rates among elderly nulliparous women.

MATERIALS AND METHODS

We conducted a retrospective analysis of all nulliparous women at 34 + 0 to 41 + 6 weeks, undergoing cervical ripening by prostaglandin E2 (PGE2) vaginal insert. Study group included elderly (≥35 years) nulliparous and control group included non-elderly (<35 years) nulliparous women. Primary outcome was IoL failure rate and secondary outcome was cesarean delivery rate. Outcomes were compared between the groups by univariate analysis followed by regression analysis to adjust results to potential confounders.

RESULTS

Of 537 women undergoing IoL, 69 (12.8%) were elderly. The univariate analysis demonstrated no difference in IoL failure rate (26.5% versus 34.8%, p = 0.502) between groups. However, elderly nulliparous women had higher rates of cesarean delivery (36.2% versus 21.4%, p = 0.009). This difference was no longer significant after adjustment for maternal body mass index, indication for delivery, birth weight and gestational age at delivery.

CONCLUSION

Among nulliparous women, older maternal age is not associated with higher rates of IoL failure or cesarean deliveries.

Induction of labor in women with a uterine scar

OBJECTIVE

To evaluate the frequency of uterine rupture following induction of labor in women with a previous cesarean section. Misoprostol was compared to other methods of induction.

METHODS

A retrospective cohort study of 208 women attempting induction of labor after one previous cesarean section. Delivery data were collected retrospectively and compared. Group 1(2009-2010) was compared with Group 2 (2012-2013). In Group 1, the main method of induction was vaginal PGE2 (prostaglandin-E2), amniotomy, oxytocin or a balloon catheter. In Group 2, the dominant method of induction was an oral solution of misoprostol.

MAIN OUTCOME MEASURES

frequency of uterine rupture in the two groups.

RESULTS

Nine cases (4.3%) of uterine rupture occurred. There was no significant difference in the frequency of uterine rupture following the change of method of induction from PGE2, amniotomy, oxytocin or mechanical dilatation with a balloon catheter to orally administered misoprostol (4.1 versus 4.6%, p = 0.9). All ruptures occurred in women with no prior vaginal delivery.

CONCLUSION

The shift to oral misoprostol as the primary method of induction in women with a previous cesarean section did not increase the frequency of uterine rupture in the cohort studied.

Predicting Cesarean Delivery After Induction of Labor Among Nulliparous Women at Term

OBJECTIVE

To identify independent risk factors for cesarean delivery after induction of labor and to develop a nomogram for predicting cesarean delivery among nulliparous women undergoing induction of labor at term.

METHODS

This is a retrospective cohort study including nulliparous women with singleton, term (37 0/7 weeks of gestation or greater), cephalic pregnancies undergoing induction of labor from July 1, 2006, through May 31, 2012, at a tertiary care academic center. Inductions were identified using International Classification of Diseases, 9th Revision codes. Demographic, delivery, and outcome data were abstracted manually from the medical record. Women with a contraindication to vaginal delivery (malpresentation, abnormal placentation, prior myomectomy) were excluded. Independent risk factors for cesarean delivery were identified using logistic regression.

RESULTS

During the study period, there were 785 nulliparous inductions that met study criteria; 231 (29.4%) underwent cesarean delivery. Independent risk factors associated with an increased risk of cesarean delivery included older maternal age, shorter maternal height, greater body mass index, greater weight gain during pregnancy, older gestational age, hypertension, diabetes mellitus, and initial cervical dilation less than 3 cm. A nomogram was constructed based on the final model with a bias-corrected c-index of 0.709 (95% confidence interval 0.671-0.750).

CONCLUSION

We identified independent risk factors that can be used to predict cesarean delivery among nulliparous women undergoing induction of labor at term. If validated in other populations, the nomogram could be useful for individualized counseling of women with a combination of identifiable antepartum risk factors.

LEVEL OF EVIDENCE

II.

Umbilical cord prostaglandins in term and preterm parturition

OBJECTIVE

Prostaglandins (PGs) are considered the universal mediators of parturition. Amniotic fluid PGE2 and PGF2α concentrations increase before the onset of spontaneous labor at term, as well as during labor. This study was conducted to determine if the concentrations of umbilical cord PGE2 and PGF2α change with advancing gestational age, spontaneous labor at term, and preterm labor (with and without funisitis).

METHODS

Umbilical cord (UC) tissue samples were obtained from women (N = 158) with singleton pregnancies in the following groups: (1) term deliveries without labor (TNL; n = 20); (2) term deliveries with labor (TIL; n = 20); (3) spontaneous preterm deliveries (sPTD) with (n = 20) and without acute funisitis (n = 20); and (4) preeclampsia without labor (n = 78). The concentrations of PGs were determined in different locations of the UC. PGE2 and PGF2α were measured by specific immunoassays. Non-parametric statistics were used for analysis.

RESULTS

(1) In spontaneous preterm deliveries, the median UC PGE2 concentration was higher in cases with funisitis than in those without funisitis (233.7 pg/µg versus 87.4 pg/µg of total protein, p = 0.001); (2) the median UC PGE2 concentration in sPTD with funisitis was also higher than that obtained from samples who had undergone labor at term (233.7 pg/µg versus 116.1 pg/µg of total protein, p = 0.03); (3) the UC PGE2 and PGF2α concentration increased as a function of advancing gestational age before 36 weeks (PGE2: ρ = 0.59, p < 0.001; PGF2α: ρ = 0.39, p = 0.01), but not after 36 weeks (PGE2: ρ = -0.1, p = 0.5; PGF2α: ρ = -0.2, p = 0.2); (4) the median UC concentrations of PGE2 and PGF2α at term was similar in samples obtained from women with and without labor (PGE2: TNL 133.7 pg/µg versus TIL 116.1 pg/µg of total protein, p = 0.9; PGF2α: TNL 8.4 pg/µg versus TIL 8.1 pg/µg of total protein, p = 0.7); and (5) there was no correlation between UC PG concentration and gestational age at term pregnancy (PGE2: ρ = 0.01, p = 0.9; PGF2α: ρ = 0.07, p = 0.7).

CONCLUSIONS

(1) PGE2 concentrations in the UC are higher in the presence of acute funisitis than in the absence of this lesion; (2) spontaneous labor at term was not associated with a change in the UC concentration of PGE2 and PGF2α; and (3) the UC concentrations of PGE2 and PGF2α increased as a function of gestational age. We propose that UC PGs act as inflammatory mediators generated in the context of fetal systemic inflammation.

Factors associated with vaginal delivery in hypertensive and normotensive pregnant women submitted to labor induction with misoprostol: a cohort study

OBJECTIVE

To determine the factors associated with vaginal delivery in hypertensive and normotensive pregnant women submitted to induction of labor with misoprostol.

METHODS

A cohort study.

RESULTS

The factors associated with vaginal delivery in both normotensive and hypertensive women were, respectively, Bishop score ≥ 4 (OR = 1.87; 95% CI: 1.06-3.29; p = 0.03) and (OR = 2.31; 95% CI: 1.25-4.28; p = 0.008) and parity ≥ 1 (OR = 4.36; 95% CI: 2.16-8.80; p < 0.0001) and (OR = 2.61; 95% CI: 1.36-5.04; p = 0.004).

CONCLUSION

The factors associated with vaginal delivery were Bishop score ≥ 4 and parity ≥ 1 irrespective of whether or not the women were hypertensive.

Timing of delivery in women with diabetes in pregnancy

The incidence of both gestational and pre-gestational diabetes is increasing worldwide. The main cause of this increase is likely the concomitant increase in the incidence of global obesity, but in the case of gestational diabetes, changes in the diagnostic criteria are also a contributing factor. The adverse outcomes associated with pre-gestational diabetes are well known and have led clinicians to implement various strategies that include increased fetal surveillance and induction of labour at various gestational ages. In many cases these same strategies have been applied in clinical practice also to women with gestational diabetes despite there being differences in the type and magnitude of perinatal complications associated with this diagnosis. Despite the widespread application of these clinical practices, there is a paucity of quality data in the medical literature to guide the clinician in choosing a strategy for fetal surveillance and timing of delivery in both gestational diabetes and pre-gestational diabetes pregnancies. In the following review, we will discuss the rationale and consequences of planned delivery in gestational diabetes and pre-gestational diabetes, the evidence supporting different strategies for delivery and finally highlight future targets for research in this area.

Labor induction with prostaglandin E2: characteristics of response and prediction of failure

OBJECTIVE

To characterize the response to labor induction with prostaglandin E2 (PGE2) and to identify risk factors for induction failure.

METHODS

A prospective controlled study of women admitted for labor induction with PGE2. Maternal characteristics, Bishop score and sonographic cervical length were documented at admission. The change in cervical characteristics and the emergence of uterine contractions following each application of PGE2 were analyzed.

RESULTS

Of the 88 women who were included in the study, 19 (21.6%) failed to response to PGE2. The following factors were independently associated with induction failure: nulliparity (odds ratio [OR] = 5.9, 95% confidence interval (CI): 1.2-30.2), pre-pregnancy body mass index >25 kg/m2 (OR = 5.4, 95% CI: 1.1-26.5), Bishop score <4 (OR = 2.3, 95% CI: 1.05-14.4), cervical length <25 mm (OR = 0.2, 95% CI: 0.1-0.8) and the development of uterine contractions in response to the first application of PGE2 (OR = 0.4, 95% CI: 0.1-0.93). Overall, most women required only one (60.9%) or two (85.5%) applications of PGE2 to achieve successful induction. The number of applications of PGE2 required to achieve successful induction was related to parity and cervical status at presentation.

CONCLUSIONS

Overall, most women who eventually respond to PGE2 do so following the first two applications of PGE2, and the contribution of subsequent applications is relatively small and related to cervical status at admission.

[Adding parity to the Bishop score for term labor induction: a retrospective study]

OBJECTIVE

To evaluate the interest to add parity to the Bishop score before induction of labor by intravenous oxytocin.

PATIENTS AND METHODS

This retrospective cohort study compared cesarean section rate for induction failure by intravenous oxytocin in nulliparous and multiparous with modified Bishop score from 7 to 9. The modified Bishop score is calculated by adding 2 points to the Bishop score if the patient had a previous vaginal delivery and 0 point in nulliparous.

RESULTS

Over 2 years, 468 patients were included (201 nulliparous and 267 multiparous). Cesarean section rate for induction failure was higher for nulliparous with a modified Bishop score equal to 7 or varying between 7 and 9. These results confirm that parity is an important predicting factor of successful labor induction. In multiparous, cesarean section rates for induction failure were not significantly different with Bishop score or modified Bishop score equal to 7.

CONCLUSION

Adding 2 points for multiparity at the Bishop score did not increase cesarean for failure of labor induction with intravenous oxytocin with a modified Bishop score from 7 to 9.

A clinical prediction model to assess the risk of operative delivery

OBJECTIVE

To predict instrumental vaginal delivery or caesarean section for suspected fetal distress or failure to progress.

DESIGN

Secondary analysis of a randomised trial.

SETTING

Three academic and six non-academic teaching hospitals in the Netherlands.

POPULATION

5667 labouring women with a singleton term pregnancy in cephalic presentation.

METHODS

We developed multinomial prediction models to assess the risk of operative delivery using both antepartum (model 1) and antepartum plus intrapartum characteristics (model 2). The models were validated by bootstrapping techniques and adjusted for overfitting. Predictive performance was assessed by calibration and discrimination (area under the receiver operating characteristic), and easy-to-use nomograms were developed.

MAIN OUTCOME MEASURES

Incidence of instrumental vaginal delivery or caesarean section for fetal distress or failure to progress with respect to a spontaneous vaginal delivery (reference).

RESULTS

  375 (6.6%) and 212 (3.6%) women had an instrumental vaginal delivery or caesarean section due to fetal distress, and 433 (7.6%) and 571 (10.1%) due to failure to progress, respectively. Predictors were age, parity, previous caesarean section, diabetes, gestational age, gender, estimated birthweight (model 1) and induction of labour, oxytocin augmentation, intrapartum fever, prolonged rupture of membranes, meconium stained amniotic fluid, epidural anaesthesia, and use of ST-analysis (model 2). Both models showed excellent calibration and the receiver operating characteristics areas were 0.70-0.78 and 0.73-0.81, respectively.

CONCLUSION

  In Dutch women with a singleton term pregnancy in cephalic presentation, antepartum and intrapartum characteristics can assist in the prediction of the need for an instrumental vaginal delivery or caesarean section for fetal distress or failure to progress.

Prediction of successful labor induction by evaluation of maternal symptoms at an early stage of the misoprostol induction protocol

OBJECTIVE

This prospective observational study evaluated maternal symptoms and characteristics that predict successful labor induction with oral misoprostol.

METHODS

A total of 244 consecutive women undergoing labor induction voluntarily completed a questionnaire about subjective sensations and pain scores during the induction protocol. Maternal and neonatal characteristics were collected retrospectively from patient files. On the first day of induction, oral misoprostol (50 μg) every 4 h up to three doses was used.

RESULTS

A total of 46% of the parturients delivered or reached the active phase of labor 24 h after the initial dose of misoprostol (ID). In the whole study, 87% of the women delivered vaginally. In multivariable analysis, rupture of membranes, cervical dilatation before the initial dose, maternal sensation of painful contractions at 8 h after the initial dose, and gestational age, were found to be associated with successful labor induction.

CONCLUSIONS

Maternal sensation of painful contractions 8 h after an ID is an independent predictive factor of successful labor induction (defined as delivery or active phase of labor 24 h after beginning of induction). Other independent predictive factors are rupture of membranes, cervical dilatation before the initial dose, and gestational age.

Using a simplified Bishop score to predict vaginal delivery

OBJECTIVE

The Bishop score is the most commonly used method to assess the readiness of the cervix for induction. However, it was created without modern statistical methods. Our objective was to determine whether a simplified score can predict vaginal delivery equally well.

METHODS

Data were analyzed for 5,610 nulliparous women with singleton, uncomplicated pregnancies between 37 0/7 and 41 6/7 weeks of gestation undergoing labor induction. These women had all five components of the Bishop score recorded. Logistic regression was performed and a simplified score created with significant components. Positive and negative predictive values and positive likelihood ratios were calculated.

RESULTS

In the regression model, only dilation, station, and effacement were significantly associated with vaginal delivery (P<.01). The simplified Bishop score was then devised using these three components (range 0-9) and compared with the original Bishop score (range 0-13) for prediction of successful induction, resulting in vaginal delivery. Compared with the original Bishop score (greater than 8), the simplified Bishop score (greater than 5) had a similar or better positive predictive value (87.7% compared with 87.0%), negative predictive value (31.3% compared with 29.8%), positive likelihood ratio (2.34 compared with 2.19), and correct classification rate (51.0% compared with 47.3%). Application of the simplified Bishop score in other populations, including indicated induction and spontaneous labor at term and preterm, were associated with similar vaginal delivery rates compared with the original Bishop score.

CONCLUSION

The simplified Bishop score comprised of dilation, station, and effacement attains a similarly high predictive ability of successful induction as the original score.

LEVEL OF EVIDENCE

II.

Clinical and sonographic parameters at 37 weeks' gestation for predicting the risk of primary Cesarean delivery in nulliparous women

OBJECTIVES

To identify the clinical and sonographic parameters at 37 weeks' gestation that predict the risk of Cesarean delivery in labor for nulliparas.

METHODS

This prospective observational study recruited nulliparas with singleton pregnancies at 37 weeks' gestation. Determination of the Bishop score, ultrasound measurement of the cervical length, and fetal biometry were performed. The clinical parameters studied were maternal age, height and weight and Bishop score. The sonographic parameters included fetal biparietal diameter, femur length, abdominal circumference (AC), estimated fetal weight (EFW), amniotic fluid index and cervical length.

RESULTS

Four hundred and fifty-three women were examined; 57 women (12.6%) underwent an emergency Cesarean delivery in labor. Logistic regression analysis identified maternal age and height and fetal AC and EFW, but not cervical length or Bishop score, as the best predictors of Cesarean delivery. Of these predictors, maternal age and height and fetal AC at 37 weeks were included in a final model for risk scoring. The model was shown to have an adequate goodness of fit (P = 0.473), and the area under the receiver-operating characteristics curve was 0.758, indicating reasonably good discrimination.

CONCLUSIONS

Maternal age and height and fetal AC and EFW at 37 weeks' gestation are the most important parameters in predicting the risk of Cesarean delivery in nulliparas; sonographic measurement of the cervical length and the Bishop score were not predictive of Cesarean delivery. A predictive model using these parameters at 37 weeks provides useful information in the decision-making process regarding the mode of delivery.

Outcome of induction of labour using maternal characteristics, ultrasound assessment and biochemical state of the cervix

OBJECTIVE

To assess pre-induction sonographic, digital examination and biochemical changes in the cervix to predict induction outcome.

METHODS

Transvaginal and abdominal scans were performed in 460 women at 37-41 weeks of gestation to determine cervical length (CL), posterior cervical angle (PCA) and foetal occipital position. The Bishop Score (BS) and the absence/presence of phosphorylated form of insulin-like growth factor-binding protein-1 (phIGFBP-1) in cervical secretions were assessed. Independent parameters significantly associated with a vaginal delivery were identified.

RESULTS

A total of 340 (73.9%) women achieved a vaginal delivery following induction. Multivariate analysis indicated that significant independent predictors of vaginal delivery were CL (adjusted odds ratio [AOR]: 0.59, 95% confidence interval [CI]: 0.45-0.79), PCA (AOR: 1.89, 95% CI: 1.09-3.28) and multiparae (AOR: 10.02, 95% CI: 5.10-19.69). For a specificity of 75%, the sensitivity for prediction of vaginal delivery using the BS, the CL and the multivariate model using the identified significant independent predictors were 37.1, 46.8 and 68%, respectively.

CONCLUSION

The combination of sonographic assessment of the cervix and maternal characteristics was superior to the either BS or CL alone in the prediction of the induction outcome. Inclusion of the absence/presence of phIGFBP-1 did not further improve induction outcome.

Prelabor rupture of membranes at term requiring labor induction - a feature of occult fetal cephalopelvic disproportion?

AIM

To examine the maternal and neonatal characteristics related to labor outcome following induction for prelabor rupture of membranes (PROM) after 37 weeks' gestation.

METHOD

All singleton pregnancies delivered following spontaneous or induced labor after 37 weeks in four years were analyzed. Patients with labor induction for PROM comprised the study group. Outcome of labor was analyzed according to gestational age at delivery.

RESULTS

Among the 13,505 patients in the entire cohort, 1710 (12.7%) had labor induction for PROM. These women were older and heavier, were more nulliparas and had more large-for-gestational age (LGA) infants, higher rates of instrumental and cesarean deliveries, and a shorter mean gestation, but no difference in height, mean birth weight, or incidence of male infants. Multiple logistic regression analysis confirmed that labor induction was a weak but significant independent factor for cesarean delivery (aOR 1.18, 95% CI: 1.01-1.38). The rates of cesarean delivery significantly correlated with gestational age at delivery for both LGA (P<0.001) and non-LGA (P<0.001) infants, together with significantly increased birth weight.

CONCLUSION

The results suggest that a likely explanation for the cesarean delivery following labor induction for PROM at term in our population is underlying cephalopelvic disproportion.

Ultrasonographic measurement of cervical length in predicting mode of delivery after oxytocin induction

This study was conducted to explore the value of transvaginal ultrasonographic cervical length measurement, in addition to gestational age, maternal age, parity, Bishop score, and weight of the newborn, in predicting the mode of delivery in pregnancies in which labor is induced with oxytocin at or beyond the 40th gestational week. A total of 73 pregnancies at 40 to 42 weeks of gestation were included. After labor was induced, 29 women delivered vaginally and 44 underwent cesarean section. These groups were compared with respect to possible predictive parameters of delivery outcomes. Student t test, Pearson's correlation analysis, and logistic regression analysis were used for statistical evaluation. Mean preinduction cervical length was 26.8+/-9.9 mm in the vaginal delivery group and 34.2+/-8.1 mm in the cesarean section group (P<.05). Mean maternal age, parity, and Bishop score were significantly higher and mean weight of the newborn was significantly lower in the vaginal delivery group. Cervical length measurements showed a significant negative correlation with Bishop scores (r=-.584; P<.05). Logistic regression analysis revealed that Bishop score (likelihood ratio=.472; 95% confidence interval=.338-.658; P<.05) and weight of the newborn (likelihood ratio=1.002; 95% confidence interval=1.00007-1.003; P<.05) were significant independent predictors of the route of delivery. According to the results of this study, maternal age, parity, Bishop score, cervical length, and weight of the newborn all might affect the mode of delivery after labor induction. Bishop score, although a subjective measure, must be considered an important component of preinduction evaluation.

Misoprostol compared with prostaglandin E2 for labour induction in women at term with intact membranes and unfavourable cervix: a systematic review*

BACKGROUND

Misoprostol is a commonly used prostaglandin to induce labour. A potential risk of induction, however, is caesarean delivery, especially in women with an unfavourable cervix.

OBJECTIVES

To evaluate the use of misoprostol, compared with prostaglandin E2 (PgE2), for labour induction in women at term with an unfavourable cervix and intact membranes.

SEARCH STRATEGY

PubMed, Medline, EMBASE and the Cochrane Library were searched for articles published in any language from January 1987 to December 2005, using the keywords 'misoprostol', 'labour/labor' and 'induction'.

SELECTION CRITERIA

We identified randomised trials of women at term (> or =37 weeks of gestation) with intact membranes and unfavourable cervix, undergoing labour induction with misoprostol, orally, vaginally, sublingually or buccally, compared with PgE2 vaginally or intracervically.

DATA COLLECTION AND ANALYSIS

Caesarean delivery was the primary outcome, with tachysystole and hyperstimulation as secondary outcomes. The primary analysis compared any misoprostol with any PgE2 for all women, with a subgroup analysis for nulliparous women. Secondary analyses compared different routes and doses of misoprostol (oral or vaginal and 25 microgram or >25 microgram) and PgE2 (intracervical or vaginal). Relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. Main results Fourteen of 611 articles identified met the criteria for systematic review, with three providing information for nulliparous women. There was no difference in the risk of caesarean delivery between misoprostol and PgE2 groups (RR = 0.99, 95% CI = 0.83-1.17). Any misoprostol was associated with higher risks of tachysystole and hyperstimulation compared with any PgE2 (RR = 1.86, 95% CI = 1.01-3.43 and RR = 3.71, 95% CI = 2.00-6.88, respectively). There was a higher rate of vaginal delivery within 24 hours among all vaginal deliveries with any misoprostol compared with any PgE2 (RR = 1.14, 95% CI = 1.00-1.31), and among all deliveries, a lower rate of oxytocin use (RR = 0.71, 95% CI = 0.60-0.85) but a trend towards increased meconium staining was observed (RR = 1.22, 95% CI = 0.96-1.55). The use of misoprostol at starting dosages >25 microgram had similar findings to the primary analysis. Studies of lower misoprostol dosing (starting dose of 25 microgram) did not show any differences in the outcomes of interest, but the sample size of this secondary analysis was small (304 women, 155 receiving misoprostol).

AUTHOR'S CONCLUSIONS

Although misoprostol in women at term with an unfavourable cervix and intact membranes was more effective than PgE2 in achieving vaginal delivery within 24 hours, misoprostol does not reduce the rate of caesarean delivery either in all women or in the subgroup of nulliparous women, and it increases the rates of tachysystole and hyperstimulation. Further studies of misoprostol using a starting dose of 25 microgram may be warranted.

Factors Predicting Labor Induction Success: A Critical Analysis

Because of the risk of failed induction of labor, a variety of maternal and fetal factors as well as screening tests have been suggested to predict labor induction success. Certain characteristics of the woman (including parity, age, weight, height and body mass index), and of the fetus (including birth weight and gestational age) are associated with the success of labor induction; with parous, young women who are taller and lower weight having a higher rate of induction success. Fetuses with a lower birth weight or increased gestational age are also associated with increased induction success. The condition of the cervix at the start of induction is an important predictor, with the modified Bishop score being a widely used scoring system. The most important element of the Bishop score is dilatation. Other predictors, including transvaginal ultrasound (TVUS) and biochemical markers [including fetal fibronectin (fFN)] have been suggested. Meta-analyses of studies identified from MEDLINE, PubMed, and EMBASE and published from 1990 to October 2005 were performed evaluating the use of TVUS and fFN in predicting labor induction success in women at term with singleton gestations. Both TVUS and Bishop score predicted successful induction [likelihood ratio (LR)=1.82, 95% confidence interval (CI)=1.51-2.20 and LR=2.10, 95%CI=1.67-2.64, respectively]. As well, fFN and Bishop score predicted successful induction (LR=1.49, 95%CI=1.20-1.85, and LR=2.62, 95%CI=1.88-3.64, respectively). Although TVUS and fFN predicted successful labor induction, neither has been shown to be superior to Bishop score. Further research is needed to evaluate these potential predictors and insulin-like growth factor binding protein-1 (IGFBP-1), another potential biochemical marker.

Clinical and Ultrasound Parameters to Predict the Risk of Cesarean Delivery After Induction of Labor

OBJECTIVE

To evaluate whether factors in the maternal history and/or ultrasound parameters are useful in predicting the risk of cesarean delivery after induction of labor.

METHODS

Maternal age, height, body mass index, parity, gestational age, Bishop score, ultrasonic amniotic fluid volume, fetal head position, estimated fetal weight, and transvaginal cervical length were studied prospectively in 267 women at 36 or more weeks of gestation immediately before induction of labor. Logistic regression analysis was used to determine which factors best predicted the risk of cesarean delivery. Receiver operating characteristic curves and a resampling technique were used to evaluate the model's performance.

RESULTS

Eighty (30%) of these 267 women had cesarean delivery. Logistic regression was performed and a final model chosen, which included parity (odds ratio [OR] 20.56, 95% confidence interval [CI] 7.97-53.05, P < .001), body mass index (OR 6.17, 95% CI 2.10-18.13, P < .001), height (OR 0.94, 95% CI 0.89-0.98, P = .005), and ultrasonic transvaginal cervical length (OR 1.07, 95% CI 1.04-1.11, P < .001) as the best predictors of cesarean delivery. A risk score was calculated containing these 4 parameters, which predicted reasonably accurately the risk of cesarean delivery.

CONCLUSION

Parity, body mass index, height, and ultrasonic transvaginal cervical length are the most accurate parameters in predicting the risk of cesarean delivery after induction of labor. A predictive model using these would allow more accurate counseling and better informed consent in the decision-making process regarding induction of labor

LEVEL OF EVIDENCE

II-2.