Sonographic cervical length as a predictor of type of delivery after induced labor

Purpose

This study was undertaken to evaluate the comparative value of sonographic cervical length and the Bishop score in predicting the type of delivery after induced labor.

Methods

The Bishop score was determined by digital examination and cervical length by transvaginal sonography in 177 women.

Results

The best cut-off points for predicting type of delivery found with ROC curves were 25.2?mm for cervical length and 5 for the Bishop score. The Bishop score was not predictive of type of delivery. Cervical length was related to type of delivery in women with Bishop score ≤5. A logistic regression model showed that only cervical length ≥25.2?mm, parity, and body mass index significantly predicted the likelihood of cesarean delivery.

Conclusions

Our study suggests that both Bishop score and sonographic cervical length can contribute to predicting type of delivery after labor induction, but cervical length is a better predictor of the risk of cesarean delivery.     

Transvaginal ultrasonography of the uterine cervix before induction of labor]

OBJECTIVE: To compare the Bishop score and transvaginal ultrasonographic measurement of cervical length for predicting the mode of delivery following medically indicated induction of labor in term patients. METHOD: The study was conducted prospectively among 134 women who required medically indicated induction of labor. Inclusion criteria were singleton pregnancy, gestational age > or = 37 weeks of amenorrhea, cephalic presentation, and intact fetal membranes. Transvaginal ultrasonography was performed for measurement of the cervical length but the patients were managed without considering this parameter. A receiver-operating characteristic curve was constructed to determine the best cut-of value of cervical length for predicting the risk of cesarean section following induction of labor. RESULTS: Thirty six patients (26.9%) underwent cesarean section and cervical dilatation at time of the cesarean section was < 8 cm in 25 cases. The Bishop score was not predictive for the mode of delivery in this study. In contrast, the cesarean section rate was significantly lower in women with a uterine cervix < 26 mm (18.9 vs 36.6%, p = 0.02). Moreover, the difference has concerned only the cesarean sections performed before 8 cm dilatation (9.5 vs 30.0%, p = 0.002). CONCLUSION: Cervical length measured with transvaginal ultrasonography is a better predictor than the Bishop score for predicting the risk of cesarean section following medically indicated induction of labor.     

Comparison of ultrasonographic cervical length and the Bishop score in predicting successful labor induction

BACKGROUND: The aim of this study was to compare the performance of the Bishop score and transvaginal ultrasonography to predict successful labor induction, and to estimate the most useful cut-off points for the two methods. METHODS: The five components of the Bishop score were assessed by digital examination and cervical length was measured by transvaginal ultrasonography in 177 women with a single pregnancy, 36-42 weeks of gestation, and a live fetus in cephalic presentation before induction of labor. RESULTS: Multiple regression analysis showed that the Bishop score, cervical length, and parity provided independent contribution in the prediction of the likelihood of delivering vaginally within 60 h. The only component of the Bishop score that was independently predictive of the probability of vaginal delivery within 60 h was station. The best cut-off points for predicting successful induction using receiver operating characteristic curves were 24 mm for cervical length and 4 for the Bishop score. Cervical length was a better predictor than the Bishop score (sensitivity and specificity of 66 and 77% versus 77 and 56%, respectively). Kaplan-Meier survival curves showed that cervical length was the best discriminator of successful induction. CONCLUSION: Measurement of cervical length by transvaginal ultrasonography is a better predictor of success in labor induction with both topical prostaglandin and oxytocin.     

Digital and transvaginal ultrasound cervical assessment for prediction of successful labor induction.

OBJECTIVE: To compare the values of preinduction transvaginal cervical length measurements and Bishop score to predict successful labor induction. METHODS: A prospective, observational trial of nulliparous women undergoing labor induction. Inclusion criteria were gestational age between 36 and 42 weeks, singleton cephalic presentation of the fetus, and intact membranes. Preinduction cervical ripening was performed using 25 microg intravaginal misoprostol (PGE1), repeated every 4 h, up to a maximum of 3 doses. Induction was subsequently continued by oxytocin and amniotomy. RESULTS: A total of 43 women met the inclusion criteria. Mean preinduction cervical length for women with successful or failed labor induction was 26 mm (95% Confidence interval [CI], 27-32) and 34 mm (95% CI, 33-38), respectively (P=0.002). Mean Bishop scores for successful and failed induction groups were 5.4 (95% CI, 5.2-6.2) and 3.1 (95% CI, 2.8-3.5), respectively (P=0.003). CONCLUSION: Digital examination and transvaginal ultrasound of the cervix predict successful labor induction with reasonable accuracy.     

Pre-induction sonographic assessment of the cervix in the prediction of successful induction of labour in nulliparous women

OBJECTIVE: To compare the efficacy of ultrasonographic cervical assessment with Bishop score before induction of labour in predicting the success of labour induction in nulliparous women. METHODS: This is a prospective study conducted in 138 women who underwent cervical assessment with transvaginal sonography followed by digital cervical assessment using Bishop score before induction of labour. Ultrasonographic parameters evaluated were cervical length, posterior cervical angle and funnelling were blinded to the managing physicians. Statistical analysis was carried out using Mann-Whitney test, chi2 test, receiver operating characteristics curves and logistic regression analysis. RESULTS: Induction of labour was successful in 106 (76.8%) of the women. Multiple logistic regression analysis demonstrated cervical length and posterior cervical angle assessed by transvaginal sonography as independent predictors of successful outcome after induction of labour. Neither Bishop score nor its individual parameters were found to be significant in the regression analysis. The area under the receiver operating characteristic curve for cervical length and posterior cervical angle was greater than that of the Bishop score in predicting a successful labour induction. The best cut-off point for the parameters in receiver operating characteristics curve was 3.0 cm for cervical length and 100 degrees for posterior cervical angle. Cervical length of 3.0 cm had a sensitivity of 84.9%, and a specificity of 90.6% and a posterior cervical angle of 100 degrees with 65% and 72%, respectively. CONCLUSIONS: Transvaginal sonographic assessment of cervical length and posterior cervical angle is better than conventional Bishop score in predicting successful labour induction in nulliparous women.     

Transvaginal ultrasonographic cervical measurement as a predictor of successful labor induction

OBJECTIVE: Our purpose was to compare transvaginal cervical measurement and the Bishop score as indicators of duration of labor and successful induction of labor at term.Study Design: This prospective observational study recruited women with singleton gestations scheduled for induction of labor at > or =37 weeks. Transvaginal ultrasonographic measurement of cervical length was performed and the Bishop score was determined, each by operators masked to the other measurement. Data were collected on parity, gestational age, mode of delivery, induction agent, induction-to-delivery interval, Bishop score, and cervical length measurement. RESULTS: A total of 77 women were analyzed. Vaginal delivery occurred in 69%. Both Bishop score and cervical length showed linear correlation with duration of labor (R(2) = 0.43, P <. 001; R(2) = 0.48, P <.001; respectively). Women with cervical length <3.0 cm had shorter labors (P <.001) and were more likely to be delivered vaginally (P <.001). Women with a Bishop score >4 also had shorter labors and were more likely to be delivered vaginally, with similar P values. A logistic regression model identified cervical length and parity as the only independent predictors of vaginal delivery. CONCLUSIONS: Both ultrasonographically measured cervical length and Bishop score predict duration of labor and likelihood of vaginal delivery. However, only cervical length and parity were independent predictors of mode of delivery.     

Elective induction of labor: failure to follow guidelines and risk of cesarean delivery

BACKGROUND: Estimate the frequency of failure to follow the French consensus guidelines for elective induction, and assess how failure affects the rate of cesarean delivery. METHODS: We compared cesarean rates according to mode of onset of labor among 5,046 low-risk patients. Violation of the guidelines was defined as induction before 38 weeks or with a Bishop score <5 or with prostaglandins. The cesarean risk was analysed with a bivariable and then a multivariable analysis, which used a multilevel logistic model. RESULTS: Women with electively induced and spontaneous labor had identical cesarean rates (4.1%). The guidelines were not followed in 23.2% of elective inductions. The risk of cesarean was higher after induction with a Bishop score <5, than after spontaneous labor (adjusted OR=4.1, 95% CI [1.3-12.9]), while elective induction with a favourable cervix did not increase the cesarean risk. In nulliparas, failure to follow the guidelines tripled the risk of cesarean (adjusted OR=3.2 [1.0-10.2]). On the other hand, elective induction of labor for women with a favourable cervix did not increase the risk of cesarean over the risk with spontaneous labor. CONCLUSION: Elective induction does not appear to increase the cesarean rate when the guidelines are met. Electively inducing labor with a low Bishop score increased the risk of cesarean, especially in nulliparas.     

The labor induction: integrated clinical and sonographic variables that predict the outcome.

OBJECTIVE: To analyze the clinical and sonographic variables that predicts the success of labor induction. STUDY DESIGN: We studied the Bishop score, cervical length and parity in 196 pregnant women in the prediction of successful vaginal delivery within 24 h of induction. Logistic regression and segmentation analysis were performed. RESULTS: Cervical length (odds ratio (OR) 1.089, P<0.001), Bishop score (OR 0.751, P=0.001) and parity (OR 4.7, P<0.001) predict the success of labor induction. In a global analysis of the variables studied, the best statistic sequence that predicts the labor induction was found when we introduced parity in the first place. The success of labor induction in nulliparous was 50.8 and 83.3% in multiparous women (P=0.0001). CONCLUSIONS: Cervical length, Bishop score and parity, integrated in a flow chart, provide independent prediction of vaginal delivery within 24 h of induction.     

Variables that predict the success of labor induction

BACKGROUND. To analyze the clinical and sonographic variables that affect the success of labor induction. METHODS. Bishop score, cervical length, and parity were studied in 196 pregnant women in the prediction of successful vaginal delivery within 24 hr of induction. Logistic regression and segmentation analysis were performed. RESULTS. Cervical length [odds ratio (OR) 1.089, P<0.001], Bishop score (OR 0.751, P=0.001), and parity (OR 6.85, P<0.001) predict the success of labor induction. The best cut-off points for cervical length were <16.5, 16.5--27, and >27 mm (P=0.0016). In the analysis of the Bishop score, we also obtained three discriminatory points, 0, 1--4, and >4 (P=0.0006), that best predict the labor induction. Finally, in a global analysis of the variables studied, the best statistic sequence that predicts the labor induction was found when we introduced parity in the first place. The success of labor induction in nulliparous was 50.77 and 83.33% in multiparous (P=0.0001). CONCLUSIONS. Cervical length, Bishop score, and parity predict the success of labor induction.     

Can measurement of cervical length,fetal head position and posterior cervical angle be an alternative method to Bishop score in the prediction of successful labor induction?

Aim: The purpose of this study was to evaluate sonographic cervical length, posterior cervical angle and fetal head position in predicting successful induction of labor at term can be an alternative method to Bishop score.

Methods: This prospective observational study recruited 223 women with singleton gestations scheduled for induction of labor at 37–42 weeks. Parity, body mass index, Bishop score, fetal head position, cervical angle measurement and cervical length was investigated to predict successful labor induction. Multiple regression analysis was performed to determine the parameters in the prediction of successful vaginal delivery within 24 hours.

Results: Forty-five patients were excluded because of cesarean section performed for other reasons than arrest of dilation or fetal head descent (43 fetal distress, 2 cord prolapsus). Remaining 178 patients were divided into two groups according to duration of delivery time. 139 patients delivered within 24 hours were classified as group I, 39 patients delivered after 24 hours were classified as group II. Percentage of multiparity was statistically significantly higher in group I than in group II [59 (42.4%), 9 (23.0%) respectively, p?=?0.009]. Cervical length was statistically significantly shorter in group I than in group II [23.1?±?7.42?mm, 31.3?±?6.83?mm respectively, p?<?0.001]. Bishop score was statistically significantly higher in group I than in group II [3 (1–4), 1 (1–4) respectively, p?<?0.001]. Posterior cervical angle was statistically significantly higher in group I than in group II [100.1?±?17.2, 92.7?±?21.4 respectively, p?=?0.007]. According to the fetal head position, there was no statistically significant difference in labor duration between the groups (p?=?0.787). In the multivariate regression analysis of variables, multiparity, cervical length and Bishop score were statistically significantly predictive in successful labor induction.

Conclusion: Multiparity status, cervical length, posterior cervical angle and Bishop score can predict successful labor induction, but fetal head position is not predictive in successful labor induction.     

Comparison of the Bishop score, body mass index and transvaginal cervical length in predicting the success of labor induction

Purpose  To evaluate the role of ultrasonographic and various maternal and fetal parameters in predicting successful labor induction. Methods  Body mass index, cervical length, dilatation, effacement, Bishop score, parity, maternal age and birth weight were evaluated in 189 singleton pregnant women at 37–42 weeks of gestation and having induction of labor. All underwent induction of labor with oxytocin. Body mass index was calculated using the formula weight (kg)/height² (m), cervical measurement was performed by transvaginal ultrasonography and Bishop score was determined by digital examination of cervix. Results  Logistic regression analysis indicated that the cervical length and body mass index were independent variables in determining the risk of cesarean section (OR = 1.206, P = 0.000, CI 95% = 1.117–1.303; OR = 1.223, P = 0.007, CI 95% = 1.058–1.414 respectively). In multiple linear regression analysis, the effect of cervical length and body mass index on induction delivery interval was found to be statistically significant (t = 5.738, P = 0.000; t = 2.680, P = 0.009, respectively). ROC curve showed that the best parameter in predicting the risk of cesarean section was cervical length and that cervical length and body mass index were better parameters compared to the Bishop score (the areas under the curve are 0.819, 0.701 and 0.416, respectively). Conclusions  Body mass index and transvaginal cervical length were better predictors compared to the Bishop score in determining the success of labor induction.     

Comparison of pre-induction ultrasonographic cervical length and Bishop score in predicting risk of cesarean section after labor induction with prostaglandins

OBJECTIVE: To compare pre-induction ultrasonographic cervical length and Bishop score in predicting risk of caesarean section after labor induction with prostaglandins. PATIENTS AND METHODS: Assessment of the Bishop score and measurement of the cervical length by transvaginal sonography were performed by two operators, blinded to each other's results among women with singleton pregnancies at between 34(+0) - 41(+3) weeks of gestation requiring induction of labor with prostaglandins for medical indications. Fisher's exact test and regression logistic models were used for statistics analysis. In order to measure the strength of the association between ultrasonographic cervical length or Bishop score on one hand, and the caesarean sections rate (global or for failed induction or failure to progress) on the other hand, we computed odds ratios with 95% confidence interval. RESULTS: Among the 266 patients included in the study, multivariate analysis has shown that only Bishop score was predictive for the global caesarean section risk (OR [95% CI] 0.63 [0.45-0.87] ; P =0.005). However, neither Bishop score (OR [95% CI] 0.68 [0.42-1.09] ; P =0.11), nor ultrasonographic cervical length (OR [95% CI] 1.01 [0.95-1.08] ; P =0.59) was predictive for failed induction or failure to progress caesarean section risk. DISCUSSION AND CONCLUSION: The Bishop score appears to be a better predictor of the global caesarean section risk than ultrasonographic cervical length after induction of labor for medical reasons.     

The use of sonographic cervical length assessment for the prediction of time from induction to delivery

Objective: The objective of this study is to investigate the role of trans-vaginal cervical length measurement in the prediction of the interval to successful vaginal delivery after induction of labor with balloon catheter.

Methods: In this prospective study of cervical length measurement before induction of labor, singleton pregnancies that underwent induction of labor between 37 and 42 weeks of gestation were included. The data collected included trans-vaginal sonographic cervical measurements followed by digital cervical assessment. Bishop score was used to quantify digital assessment (before induction of labor).

Results: During the study period, 71 patients were included in the study. A statistically significant linear correlation was found between sonographic cervical length prior to induction of labor and the time of delivery (Pearson correlation 0.335; p values 0.005). Of the 57 vaginal deliveries, 27 patients had a cervical length of less than 28?mm. Patients with a cervical length of less than 28?mm had a significantly shorter time to delivery compared to patients with more than 28?mm length (20.4 versus 28.7, respectively; p value?=?0.019). Cervical length of 28?mm remained significantly correlated even after performing several logistic regression models in order to control for confounders such as parity and age. In addition, a correlation was found between Bishop scores of above 7 to the time to delivery.

Conclusions: Cervical length is correlated linearly to the time interval between induction of labor and delivery. A cervical length of less than 28?mm was found to be statistically significant in predicting a shorter time to delivery.     

Ultrasound and clinical predictors for Caesarean delivery after labour induction at term

OBJECTIVE: To assess the relationship of ultrasound assessment for amniotic fluid, fetal weight, cervical length, cervical funneling and clinical factors on the risk of Caesarean delivery after labour induction at term. METHODS: On hundred and fifty-two women scheduled for labour induction at term agreed to participate. Sonography was performed to obtain fetal biometry, amniotic fluid index and cervical length and to detect funneling at the internal cervical os. The sonographic findings were concealed. Study women received standard care during labour induction. RESULTS: On univariate analysis using Fisher's exact test, parity, cervical length and Bishop score were associated with Caesarean delivery. Following multivariable logistic regression analysis, only nulliparity (adjusted odds ratio (AOR) 5.2 (95% CI 2.2-12.2): P<0.001) and transvaginal ultrasound-determined cervical length of more than 20 mm (AOR 2.8 (95% CI 1.0-7.4): P=0.04) were independent predictors of Caesarean delivery in labour induction. Maternal age, maternal height, gestational age, indication for labour induction, amniotic fluid index, cervical funneling and ultrasound-estimated fetal weight did not predict Caesarean delivery. CONCLUSION: In women who had undergone labour induction at term with a singleton fetus, nulliparity and cervical length of more than 20 mm on transvaginal sonography were independent predictors of Caesarean delivery. This information is helpful for pre-induction counselling.     

Cervical assessment in women with threatened preterm labor.

OBJECTIVE: The aim of the study was to examine the clinical value of cervical assessment by transvaginal ultrasonography in women with symptoms of preterm labor. METHODS: We prospectively evaluated 172 women with singleton pregnancies and symptoms of preterm labor. Seventy of them were nulliparas, while 102 were multiparas. Gestational age ranged between 24 and 34 wks. All women underwent cervical assessment with transvaginal ultrasonography and were given intravenous tocolytics. The only parameter evaluated was cervical length. Women with multiple pregnancies, gestational age <24 wks or >34 wks, cervical dilatation >2 cm, placenta praevia, premature rupture of membranes, or cervical cerclage were excluded from the study. The outcome measure was delivery before 34 wks gestation. RESULTS: The preterm delivery rate before 34 wks was 37%. The sensitivity and the specificity of a cervical length of less than 20 mm was 60 and 53.8% and 97.7 and 95.2% for nulliparas and multiparas, respectively. A cervical length <20 mm was also 93.7% predictive of preterm delivery in nulliparas and 87.5% in multiparas, while the corresponding numbers for its negative predictive value (NPV) were 81.4 and 76.9%, respectively. CONCLUSIONS: Cervical assessment in women with symptoms of preterm labor can distinguish those at high risk for preterm delivery. Cervical sonography can be a valuable adjunct to the clinical evaluation of these patients.     

阴道超声及细胞因子预测宫颈成熟度和临产时间的初步探讨

目的　探讨阴道超声、细胞因子———白细胞介素 (IL) 6、8及人绒毛膜促性腺激素 (hCG)对足月妊娠宫颈成熟度、临产时间的预测价值。方法　检测 79例足月初产妇宫颈阴道分泌液IL 6、IL 8及hCG水平 ;通过阴道超声测量孕妇宫颈长度、宫颈内口楔形区宽度、前羊膜囊长度 ;同时进行宫颈Bishop评分。结果　 (1)IL 6、IL 8、hCG临产后水平 [分别为 (782± 5 0 8)ng/L、(10 5 3 9± 8680 )ng/L、(114± 86)IU/L]较临产前 [分别为 (15 5± 75 )ng/L、(7113± 60 5 0 )ng/L、(3 5± 2 1)IU/L]显著升高 ,差异有极显著性 (P <0 0 5 )。 (2 )IL 6、IL 8、hCG、宫颈长度、前羊膜囊长度均与宫颈Bishop评分显著相关(r=0 42、0 2 4、0 44、- 0 5 6、0 3 5 ,P <0 0 5 )。 (3 )IL 6、IL 8、宫颈长度、前羊膜囊长度、宫颈Bishop评分均与临产时间显著相关 (r=- 0 42、- 0 46、0 64、- 0 5 2、- 0 41,P <0 0 1) ;且均能预测 1周内临产 ,其中宫颈长度的预测效果最好。宫颈长度≤ 3 0mm者 ,预测其在 1周内分娩的灵敏度、特异度、阳性预测值、阴性预测值分别为 0 83、0 89、0 91、0 81。 (4)多因素分析显示 :阴道超声测量宫颈长度 ,预测宫颈成熟度和临产时间的价值优于其他指标。结论　孕妇宫颈阴道分泌液IL 6、     

Comparison of Cervical Length Measured by Transvaginal Ultrasonography and Bishop Score in Predicting Response to Labor Induction

Background

This study aims to compare the value of the Bishop score and cervical length measurement by transvaginal ultrasonography in predicting active labor within 6 h, induction-to-delivery interval, and the duration of active labor and to estimate the most useful cutoff points for the two methods.

Methods

This is a prospective comparative study of Bishop score and cervical length measured by transvaginal sonography on 62 nulliparous subjects who underwent induction of labor.

Results

The Bishop score of the subjects ranged from two to seven (2–7). The mean Bishop in this study population was 4.37 + 1.23. The mean cervical length in this study was 25.59 + 6.07. Bishop score was highly significant (P value < 0.0001) in predicting active phase of labor as compared to cervical length (P = 0.004). The best cutoff value for Bishop score to predict induction of labor within 6 h was more than 4 with sensitivity of 69% and specificity of 79%. Similarly, best cutoff value for cervical length to predict induction of labor within 6 h was less than or equal to 25 mm with sensitivity of 51% and specificity of 70%. Bishop score was more significant (P = 0.001) in predicting induction-to-delivery interval within 12 h as compared to cervical length (P = 0.01).

Conclusion

The Bishop score was superior in predicting the response to induction as compared to the cervical length measured by transvaginal ultrasonography.

     

Risk of cesarean delivery after induction at term in nulliparous women with an unfavorable cervix

OBJECTIVE: The purpose of this study was to evaluate the effect of induction on the route of delivery in nulliparous women laboring at term in a community hospital system. STUDY DESIGN: From April 1997 to October 1999, there were 7282 deliveries in nulliparous patients who met inclusion criteria. Cesarean delivery rates were calculated for patients in spontaneous labor and for patients who underwent induction. RESULTS: Among 4635 women (63.7%) in spontaneous labor, the cesarean delivery rate was 11.5% versus 23.7% among the 2647 (36.3%) patients who underwent induction. An important variable that affected the delivery route was the Bishop score at the initiation of the induction. The cesarean delivery rate was 31.5% among patients whose Bishop score was <5 at induction versus 18.1% for patients with a score > or =5(P <.001). CONCLUSION: The induction of labor in nulliparous patients, especially those women with an unfavorable cervix as measured by Bishop score, is associated with a significantly increased risk of cesarean delivery.     

Transvaginal ultrasonic evaluation of the thickness of the section of the uterine wall in previous cesarean sections]

BACKGROUND: The aim of this study is to evaluate accuracy of transvaginal sonographic examination of the lower uterine segment in pregnant women with previous cesarean section. METHODS: Sixty-one pregnant women between 37 and 40 weeks of gestation, with previous cesarean section underwent transvaginal ultrasonography. Wall thickness of the lower uterine segment, the length of cervix, dilation of the isthmus uteri were measured. On the basis of the surgical findings (in 53 patients) and outcome of the trial of labor (in 8 patients) a Score was assigned to the pregnant women: Score 1 to the women who had good healing or a trial of labor without complications; Score 2 to the women with a thin or discontinued scar and in case of threatened rupture of the uterus in the trial of labor. RESULTS: The mean thickness of the lower uterine segment is 3.82 mm +/- 0.99 mm. The Score 1 group shows a mean thickness of 4.2 mm +/- 2.5 mm, and the Score 2 group a mean thickness of 2.8 mm +/- 1.06 mm. The transvaginal sonographic examination provides a sensitivity and a specificity respectively of 100 and 75%, for a thickness cut-off of 3.5 mm, and a positive and negative predictive values of 60.7% and 100% respectively. CONCLUSIONS: The transvaginal sonographic evaluation of the lower uterine segment improves therefore the obstetrical decision-making regarding the trial of labor in women with previous cesarean section.     

Factors associated with the length of the latent phase during labor induction

OBJECTIVE: To evaluate the factors that are associated with the length of the latent phase during labor induction in nulliparous women. STUDY DESIGN: During a 6-month period, all nulliparous women with a viable fetus of at least 36 weeks gestation who underwent induction of labor were identified. Demographic and intrapartum data were abstracted from the medical record. In an effort to understand the association of different factors with the length of the latent phase, both univariable and multivariable analyses were employed. RESULTS: The median length of the latent phase for the women available for analysis (N=397) was 384 min with an interquartile range of 240-604 min. In univariable analysis, a greater maternal age, a medical indication for induction, and unripe cervical status at admission (assessed by either modified Bishop score or use of cervical ripening agents) were significantly associated with a latent phase of at least 12 h. In multivariable analysis, the only variables that continued to be independently associated with a latent phase of at least 12 h were modified Bishop scores of 0-2 (adjusted odds ratio 42.0, 95% confidence interval 9.7, 183.2) and 3-5 (adjusted odds ratio 9.3, 95% confidence interval 2.1, 40.9). CONCLUSION: A woman's modified Bishop score at admission for labor induction, but not other risk factors typically associated with cesarean, is associated with length of the latent phase.