Predictors of newborn admission after labour induction at term: Bishop score, pre-induction ultrasonography and clinical risk factors

INTRODUCTION

Following labour induction at term, 12 percent of neonates can expected to be admitted to the neonatal intensive care unit. We aimed to evaluate the Bishop score, pre-induction ultrasonography (US) assessment of amniotic fluid, foetal weight and cervical length, and pre-induction and intrapartum risk factors as predictors of neonatal admission.

METHODS

152 women at term, scheduled for labour induction, consented to participate in this prospective study. Transabdominal US was performed to obtain foetal biometry and amniotic fluid index, followed by transvaginal US to measure cervical length. US findings were concealed. The Bishop score was obtained at initiation of labour induction. Pre-induction and intrapartum risk factors were also considered in the multivariate logistic regression analysis. All study women received standard care.

RESULTS

On univariate analysis, factors associated with neonatal admission were: gestational age at less than or equal to 40 weeks, labour induction for diabetes mellitus, Bishop score of less than 5 at initiation of labour induction, estimated foetal weight of less than 2.5 kg by US, induction to delivery interval of more than 24 hours, caesarean delivery and umbilical cord blood pH of less than 7.1. Cervical length of greater than 20 mm on transvaginal US (p-value is 0.10) was not significant. After multivariate logistic regression analysis, controlling for the significant variables, only the unfavourable Bishop score (adjusted OR 4.2; 95% CI 1.2-13.8; p-value is 0.02) and caesarean delivery (adjusted OR 3.9; 95% CI 1.1-13.7; p-value is 0.035) were independent predictors of neonatal admission.

CONCLUSION

The identification of an unfavourable Bishop score as an independent predictor of neonatal admission is useful in the counselling of women who are considering labour induction.

A new insertion technique for the transcervical Foley catheter used for cervical ripening

OBJECTIVE

To describe a new placement technique for the transcervical Foley catheter that may succeed when other methods have failed.

STUDY DESIGN

Sixteen patients were identified as candidates for placement of a transcervical Foley catheter for cervical ripening, but all had failed attempted placement using the classically described methods. Our new placement technique involved the use of a 5 French rigid catheter guide inserted into the Foley catheter to make the catheter rigid and to ease insertion. RESLLTS: Placement was 100% successful in all 16 patients using the new insertion technique.

CONCLUSION

The use of a rigid stylet during insertion increases the chances of success. The ease of insertion using this technique makes the use of a Foley catheter for cervical ripening a valuable option.

Intracervical prostaglandins for induction of labour

BACKGROUND

Prostaglandins have been used for cervical ripening and induction of labour since the 1970s. The goal of the administration of prostaglandins in the process of induction of labour is to achieve cervical ripening before the onset of contractions. One of the routes of administration that was proposed is intracervical. Using this route, prostaglandins are less easy to administer and the need for exposing the cervix may cause discomfort to the woman.

OBJECTIVES

To determine the effects of intracervical prostaglandins for third trimester cervical ripening or induction of labour compared with placebo/no treatment and with vaginal prostaglandins (except misoprostol).

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (August 2007) and bibliographies of relevant papers.

SELECTION CRITERIA

Clinical trials comparing intracervical prostaglandins used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods (vaginal prostaglandins, except misoprostol).

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction.

MAIN RESULTS

Fifty-six trials (7738 women) are included. INTRACERVICAL PGE2 WITH PLACEBO/NO TREATMENT: 28 TRIALS, 3764 WOMEN: Four studies reported the number of women who did not achieve vaginal delivery within 24 hours, showing a decreased risk with PGE2 (relative risk (RR) 0.61; 95% confidence interval (CI) 0.47 to 0.79). There was a small, and statistically non-significant, reduction of the risk of caesarean section when PGE2 was used (RR 0.88; 95% CI 0.77 to 1.00). The finding was statistically significant in a subgroup of women with intact membranes and unfavourable cervix only (RR 0.82; 95% CI 0.68 to 0.98). The risk of hyperstimulation with fetal heart rate (FHR) changes was not significantly increased (RR 1.21; 95% CI 0.72 to 2.05). However, the risk of hyperstimulation without FHR changes was significantly increased (RR 1.59; 95% CI 1.09 to 2.33. INTRACERVICAL PGE2 WITH INTRAVAGINAL PGE2: 29 TRIALS, 3881 WOMEN: The risk of not achieving vaginal delivery within 24 hours was increased with intracervical PGE2 (RR 1.26; 95% CI 1.12 to 1.41). There was no change in the risk of caesarean section (RR 1.07; 95% CI 0.93 to 1.22). The risks of hyperstimulation with FHR changes (RR 0.76; 95% CI 0.39 to 1.49) and without FHR changes (RR 0.80; 95% CI 0.56 to 1.15) were non-significantly different with the two methods of PGE2 administration. Only one trial with small sample size reported on women's views, with no difference between groups. INTRACERVICAL PGE2 LOW DOSE WITH INTRACERVICAL PGE2 HIGH DOSE: TWO TRIALS, 102 WOMEN: The trials are too small to provide any useful information.

AUTHORS' CONCLUSIONS

Intracervical prostaglandins are effective compared to placebo, but appear inferior when compared to intravaginal prostaglandins.

Frequency domain near-infrared spectroscopy of the uterine cervix during cervical ripening

OBJECTIVE

Preterm labor is a common obstetric complication. Clinical evaluation of cervical ripening to predict preterm labor has a substantial inter- and intraobserver variability. We used frequency domain near-infrared spectroscopy (FD-NIRS) to non-invasively investigate the changes of the optical properties (i.e., absorption and scattering of light) in the uterine cervix during drug-induced cervical ripening.

METHODS

Ten volunteers scheduled for abortion were examined. Optical properties of the uterine cervix were measured and physiological parameters were calculated prior to and after induction of cervical ripening using topical misoprostol. Mean relative changes, +/-standard error of the mean as well as statistical significance using the t-test were calculated for oxy- and deoxyhemoglobin, total hemoglobin, oxygen-saturation, and water. The wavelength-dependent decrease of scattering (scatter power) was calculated by an exponential fit and tested with the Wilcoxon test.

RESULTS

Misoprostol induced a decrease in total hemoglobin of 21 +/- 6% (P < 0.05), a decrease in oxyhemoglobin of 22 +/- 6% (P < 0.05), a decrease in deoxyhemoglobin of 16 +/- 11% and an increase of 36 +/- 8% (P < 0.005) in water content. The scatter power was significantly lower (P < 0.05) after cervical ripening.

CONCLUSION

Our results show that FD-NIRS is a promising diagnostic tool to detect changes in cervical concentrations of hemoglobin and water. A severe tissue edema, probably due to a hormone-induced inflammatory process, seems to be important for cervical ripening. The reduction in total hemoglobin is likely to be a consequence of the increased water content of the tissue resulting in a dramatic increase of the distance between vessels. We propose this technology to assess the cervical ripening and eventually to predict preterm labor.

Mifepristone versus laminaria: a randomized controlled trial of cervical ripening in midtrimester termination

BACKGROUND

Mifepristone was compared with laminaria for cervical ripening in second-trimester induction of labor (IOL).

STUDY DESIGN

We performed a randomized, controlled, open-label study of women undergoing second-trimester IOL for fetal demise, aneuploidy or anomalies at a single tertiary care center from January 2004 to May 2006. Main outcome measures were induction-to-delivery time and pain with cervical ripening.

RESULTS

Of 50 eligible women, 37 were enrolled in the study, of whom 33 completed the study: 16 were randomized to laminaria and 17 to mifepristone. Induction-to-delivery time was significantly shorter in the mifepristone arm (mean=10 h vs. 16 h, p=.01; median=7.5 h vs. 13.4 h, p=.01). Pain with cervical ripening was also significantly less in the mifepristone group than in the laminaria group (median=1 vs. 6 on an 11-point visual analogue scale, p<.001). Maternal age, parity, gestational age, fetal demise prior to induction, need for postpartum curettage, blood loss, pain during induction, delivery and at the time of discharge were not significantly different between the two groups.

CONCLUSION

Mifepristone shortens the induction-to-delivery time and decreases pain with cervical ripening when compared with laminaria for second-trimester induction.

Transcervical Foley catheter with and without extraamniotic saline infusion for labor induction: a randomized controlled trial

OBJECTIVE

To compare the efficacy of transcervical Foley catheter alone (Foley) to transcervical Foley catheter with extraamniotic saline infusion for labor induction and cervical ripening in women with an unfavorable cervix.

METHODS

This was a multicenter, randomized, controlled trial of women presenting for labor induction with a singleton, cephalic fetus, intact membranes, and unfavorable cervix (Bishop score 6 or less). Eligible women were randomly assigned to receive either Foley catheter alone or Foley catheter with extraamniotic saline infusion. All women received concurrent oxytocin administration. The primary study outcome was the induction-to-delivery interval. Secondary outcomes included cesarean delivery, maternal infectious outcomes, and immediate neonatal outcomes. Analysis was by intent to treat.

RESULTS

One hundred eighty-eight women met eligibility criteria and were randomly assigned (Foley plus extraamniotic saline infusion, n=97; Foley, n=91). Baseline demographic characteristics, including parity, gestational age, and Bishop score were similar between the study groups. The median induction-to-delivery interval in the extraamniotic saline infusion arm (12.6 hours, interquartile range 9.3-18.8 hours) was similar to that in the Foley arm (13.4 hours, interquartile range 9.6-17.5 hours) (P=. 70). The proportion of women delivered by 24 hours was comparable between groups (delivery 24 hours, extraamniotic saline infusion 89.7%, Foley 87.9%, P=.70), as was the rate of cesarean delivery (Foley 18.7%, extraamniotic saline infusion 27.8%, P=.14). No significant differences were noted between the study groups with respect to rate of chorioamnionitis, endometritis, or immediate birth outcomes.

CONCLUSION

In women with an unfavorable cervix, the addition of extraamniotic saline infusion to a transcervical Foley catheter does not improve efficacy for labor induction.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00442663

LEVEL OF EVIDENCE

I.

Predicting a failed induction

BACKGROUND

A failed induction usually refers to failure to progress to the active phase of labour; however, there is no consensus regarding when an induction has failed.

AIMS

To investigate the factors (particularly length of latent phase) that may influence mode of birth for women undergoing Syntocinon induction of labour.

METHODS

A retrospective analysis of 978 nulliparous women undergoing Syntocinon induction of labour following artificial or spontaneous rupture of membranes was performed.

RESULTS

As the length of the latent phase increased, the likelihood of birth by caesarean section increased significantly (P < 0.001). After ten hours of Syntocinon administration, the 8% of women not in the active phase of labour had approximately a 75% chance of being delivered by emergency caesarean section and after 12 h the chance was almost 90%. Multivariate analysis also suggested an association between birth by caesarean section and use of prostaglandin gel (P < 0.001) or mechanical methods of cervical priming (P = 0.004), maternal height < 155 cm (P = 0.020) and cervical dilation prior to commencement of Syntocinon (P = 0.018).

CONCLUSIONS

It would seem reasonable to continue a Syntocinon infusion for at least ten hours in women undergoing induction who have yet to reach the active phase of labour ( 4 cm), and unclear benefit in continuing an induction beyond 12 h. The duration of latent phase is a helpful predictor of subsequent mode of birth.

Misoprostol use for cervical ripening and induction of labour in a Nigerian teaching hospital

CONTEXT

Induction of labor is always a challenge to many an obstetrician more so when the cervix is unfavorable.

OBJECTIVES

To determine the efficacy and safety ofmisoprostol in cervical ripening and labour induction.

MATERIALS AND METHOD

Aprospective study spanning 2 years and involving 151 patients admitted for cervical ripening and induction of labor at Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria. 50 microgram (mcg) ofmisoprostol was inserted vaginally every 4 hours until cervix became favorable or onset of labor.

RESULTS

Main indications for induction of labour were prolonged pregnancy and hypertensive diseases of pregnancy. An average of 2 insertions of 50 mcg tablet was used to achieve cervical ripening in 107 patients (71%) and 80% (120) had spontaneous labor within 10 hours of insertion. The mean insertion-labor interval was 7.86 hours (SD +/- 2.5). The average duration of labour was 9.36 hours (SD +/- 2.9). Vaginal delivery was achieved in 96% of the patients. Uterine hyperstimulation occurred in 9 patients but there was no case of uterine rupture.

CONCLUSION

Misoprostol was effective and safe in cervical ripening and induction of labor with a vaginal delivery rate of 96%. It should be an essential drug in obstetric practice especially in low resource settings.

Cervical priming with sublingual misoprostol prior to insertion of an intrauterine device in nulliparous women: a randomized controlled trial

BACKGROUND

The copper intrauterine device (IUD) is a highly effective and safe contraceptive method, also in nulliparous women. However, insertion of an IUD through a narrow cervix may be technically difficult. Misoprostol has been shown to be effective for cervical priming in non-pregnant women prior to hysteroscopy.

METHODS

Eighty nulliparous women requesting an IUD were randomly allocated to receive sublingually 400 microg misoprostol and 100 mg diclofenac (misoprostol group) or 100 mg diclofenac alone (control group) 1 h prior to IUD insertion. Cervical dilatation was measured prior to insertion using Hegar pins. Ease of insertion was judged by the investigator. Pain, bleeding and side effects were recorded at insertion and until follow-up performed one month later.

RESULTS

Following treatment with misoprostol, insertion was significantly easier than in the control group [P = 0.039, difference 19.36%, confidence interval (CI) -0.013, 39.99]. Pain estimated on a visual analogue scale (1-10) showed no evidence of a difference between the groups. The overall distribution of side effects did not differ. However, shivering was more common in the misoprostol group (P = 0.0084, difference 23.27%, CI 6.64, 39.90).

CONCLUSIONS

Misoprostol facilitates insertion of an IUD, and reduces the number of difficult and failed attempts of insertions in women with a narrow cervical canal. The optimal regimen of misoprostol remains to be defined.

Preterm labour. Cervical function and prematurity

The cervix maintains the fetus in situ during pregnancy and dilates during labour to allow delivery of the baby. Congenital or iatrogenically-induced structural abnormalities of the cervix are associated with an increased risk of preterm birth. The role of cervical infection is less clear. Cervical studies may be useful in the prediction of preterm delivery: both a shortened cervical length identified on transvaginal ultrasound examination and an increased level of fetal fibronectin in cervico-vaginal secretions are associated with an increased risk of preterm delivery. In singleton pregnancy, cervical cerclage reduces the risk of preterm birth by 25%. There is no evidence of a reduction in neonatal mortality or morbidity, and the beneficial effects of preterm birth reduction have to be set against the increased risk of maternal infection. Neither the American College of Obstetricians and Gynecologists (ACOG) nor the Royal College of Obstetricians and Gynaecologists (RCOG) has unequivocally endorsed cervical cerclage. Further work is required to define the role of the cervix in prediction and prevention of spontaneous preterm birth.

Inpatient management for a shortened cervix: who is really at risk?

OBJECTIVE

The objective of the study was to identify risk factors associated with spontaneous preterm delivery (SPD) within 2 weeks of admission in patients with a shortened cervix.

STUDY DESIGN

We reviewed records of patients hospitalized in 2003-2004 with a cervix of 25 mm or less at less than 32 weeks' gestation. The primary outcome was SPD 2 weeks or less of admission.

RESULTS

Sixty-six patients met inclusion criteria. Twelve delivered at 2 weeks or less of admission. There were no differences in maternal and gestational age at admission, history of SPD, and rate of multifetal pregnancy. Those with cervical length (CL) of 5 mm or less were more likely to deliver within 2 weeks than those with CLs 6-25 mm (50% vs 12.5%; P = .01). Logistic regression identified CL less than 5 mm as the only independent predictor of delivery within 2 weeks of admission (P = .01).

CONCLUSION

CL of less than 5 mm in patients at less than 32 weeks' gestation is associated with a high rate of SPD within 2 weeks of diagnosis.

Cervical ripening with the Foley catheter

OBJECTIVE

To evaluate maternal and neonatal outcomes in a large series of patients undergoing cervical ripening with a Foley catheter.

METHODS

The database of the Labor and Delivery Unit of the University of a teaching hospital in Italy was used to identify consecutive patients with a Bishop score (BS) of 4 or less who underwent pre-induction cervical ripening with a Foley catheter. The main outcome measures were clinical chorioamnionitis, endometritis, and suspected and culture-proven neonatal sepsis.

RESULTS

Of 602 women undergoing cervical ripening with a Foley catheter, 160 (26.6%) went into active labor without additional interventions. Oxytocin was administered immediately after removal of the Foley catheter in 188 (31.2%) of the women, and 254 (42.2%) required an application of prostaglandin E2 vaginal gel. The cesarean delivery rate was 25.6%. The median time to delivery was 1469 min (range, 94-3350 min). Of the women who gave birth vaginally, 225 (50.2%) were delivered within 24 h. Clinical chorioamnionitis and postpartum endometritis occurred in 3 (0.5%) and 6 (1.0%) of the women, respectively. Neonatal sepsis was suspected in 4 (0.7%) of the newborns but blood culture results were negative in all cases.

CONCLUSION

Transcervical use of the Foley catheter is safe for pre-induction cervical ripening, and the associated risk of maternal or perinatal infections is negligible.

Determining Cervical Ripeness and Labor Outcome

OBJECTIVE

To determine whether the magnetic resonance assessment of cervical water content using the T2 relaxation time correlated with cervical ripening, as evidenced by the time to onset of spontaneous labor, need for induction, and the incidence of cesarean delivery in women whose pregnancy reached 41 weeks of gestation.

METHODS

The cervical T2 relaxation time was calculated from magnetic resonance data obtained in a previous study of magnetic resonance pelvimetry. After consent was obtained, the patients underwent a magnetic resonance imaging (MRI) protocol consisting of a dual fast spin echo T2-weighted scan. From images of a single slice, the cervical T2 relaxation time was calculated from two different regions of interest (anterior and posterior) on the cervix. The average cervical T2 relaxation time was then correlated to obstetric outcomes linked with cervical ripening.

RESULTS

A total of 119 patients gave their consent for the study. Of these patients, 93 had optimal imaging of the cervical stroma and were included in the analysis. There was no significant correlation between the cervical T2 relaxation time and any individual component of the Bishop score or the total score. The cervical T2 relaxation time did not predict whether labor was spontaneous or induced and whether or not a woman underwent cesarean delivery.

CONCLUSION

Cervical magnetic resonance T2 relaxation times did not correlate with the clinical Bishop score or predict labor outcome in our series of women whose pregnancies reached 41 weeks of gestation. Quantifying the magnetic resonance T2 relaxation time does not appear to be useful in the assessment of cervical ripening.

LEVEL OF EVIDENCE

III.

Cervical ripening with a Foley catheter: the role of pre- and postripening ultrasound examination of the cervix

OBJECTIVE

The objective of the study was to assess sonographic changes in cervical length and posterior cervical angle in women undergoing cervical ripening with an extraamniotic Foley catheter and to determine whether pre- and postripening ultrasound parameters could help predict successful cervical ripening and the outcome of labor induction.

STUDY DESIGN

Cervical length and posterior cervical angle were measured by transvaginal sonography in 155 women with a Bishop score of 4 or less before placement of a transcervical Foley catheter for cervical ripening. At the time of Foley removal, women who did not enter active labor underwent a second ultrasound assessment of the cervix. Outcome measures were successful ripening, vaginal delivery, vaginal delivery within 24 hours, and vaginal delivery achieved with the Foley only. Multiple logistic regression models were generated to identify pre- and postripening clinical and ultrasound parameters independently associated with successful induction.

RESULTS

Forty patients (25.8%) went into active labor after spontaneous expulsion or removal of the Foley, without any additional intervention. A successful cervical ripening was obtained with the transcervical catheter in 46 women (29.6%). One hundred six women (68.4%) had vaginal delivery. No correlation was found among maternal body mass index, maternal age, clinical cervical dilatation, sonographic posterior cervical angle, and any of the outcomes of interest. Multiple logistic regression showed that preripening sonographic cervical length was an independent predictor of successful ripening (odds ratio [OR] 10.2, 95% confidence interval [CI] 3.6 to 28.5), vaginal delivery (OR 2.6, 95% CI 1.2 to 5.5), vaginal delivery achieved with only Foley (OR 17.2, 95% CI 3.9 to 76.2), and vaginal delivery within 24 hours (OR 3.3, 95% CI 1.5 to 7.3). In the subgroup of women who did not enter labor with the transcervical Foley, at the time of catheter removal, a significant change was found in sonographic cervical length (33.1 mm [12.2 to 54.1] vs 24.0 mm [7.6 to 42], P < .0001] and sonographic posterior cervical angle (110 degrees C [70-160] vs 137 degrees C [88-170], P < .0001), compared with preripening findings. Transvaginal ultrasound cervical length was the only postripening characteristic that independently predicted vaginal delivery (OR 3.5, 95% CI 1.3 to 9.1).

CONCLUSION

Transvaginal sonography seems a useful diagnostic tool to assess objectively the efficacy of the Foley catheter as ripening method and helps predict the likelihood of a successful induction of labor in individual women who require preinduction cervical ripening.

Mechanical Methods of Cervical Ripening and Labor Induction

This article reviews the safety and efficacy of mechanical agents for cervical ripening. Hygroscopic dilators, balloon catheters, and devices designed for cervical ripening have all been shown to be safe and effective for cervical ripening. Mechanical agents are as efficacious as other agents for cervical ripening. However, there is no method that has been conclusively shown to improve mode of delivery or perinatal outcome. The advantages of preinduction cervical ripening with mechanical devices include low cost, low incidence of systemic side effects, and low risk of uterine hyperstimulation.

Quantitative ultrasound assessment of the rat cervix

OBJECTIVE

The purpose of this research was to detect cervical ripening with a new quantitative ultrasound technique.

METHODS

Cervices of 13 nonpregnant and 65 timed pregnant (days 15, 17, 19, 20, and 21 of pregnancy) Sprague Dawley rats were scanned ex vivo with a 70-MHz ultrasound transducer. Ultrasound scatterer property estimates (scatterer diameter [SD], acoustic concentration [AC], and scatterer strength factor [SSF]) from the cervices were quantified and then compared to hydroxyproline and water content. Insertion loss (attenuation) was measured in 3 rats in each of the 6 groups. Discriminant analysis was used to predict gestational age group (cervical ripening) from the ultrasound variables SD, SSF, and AC.

RESULTS

Differences were observed between the groups (SD, AC, and SSF; P < .0001). Quantitative ultrasound measures changed as the cervix ripened: (1) SD increased from days 15 to 21; (2) AC decreased from days 15 to 21; and (3) SSF was the greatest in the nonpregnant group and the least in the day 21 group. Cervix hydroxyproline content increased as pregnancy progressed (P < .003) and correlated with group, SD, AC, and SSF (P < .001). Discriminant analysis of ultrasound variables predicted 56.4% of gestational group assignment (P < .001) and increased to 77% within 2 days of the predicted analysis. Cervix insertion loss was greatest for the nonpregnant group and least for the day 21 group.

CONCLUSIONS

Quantitative ultrasound predicted cervical ripening in the rat cervix, but before use in humans, quantitative ultrasound will need to predict gestational age in the later days of gestation with more precision.

Sexual Intercourse at Term and Onset of Labor

OBJECTIVE

To determine whether sexual intercourse at term hastens the onset of labor and to observe its effect on cervical status.

METHODS

Women with low-risk pregnancies at term were asked at each of their term prenatal visits whether they had engaged in penile-vaginal intercourse during the previous week. Delivery outcomes were compared between those women who were sexually active at term and those who were not. A Bishop score was assigned to each cervical examination at term, and the weekly results of the cervical examination were compared between women who were sexually active in the previous week and those who were not.

RESULTS

Forty-seven (50.5%) of 93 women reported having had sexual intercourse at term. The gestational age at delivery of those women who were sexually active at term was greater than those who were not (39.9 weeks versus 39.3 weeks; P = .001). There was no difference in Bishop score between women who had sex in the previous week and those who had not. After adjusting for the effect of time, those who were sexually active the previous week had Bishop scores that were, on average, lower by 0.26 (95% confidence interval -1.26 to 0.74, P = .61) compared with those who abstained.

CONCLUSION

Sexual intercourse at term is not associated with ripening of the cervix and does not hasten labor.

LEVEL OF EVIDENCE

II-3.

Comparison of Labor Progression Between Induced and Noninduced Multiparous Women

OBJECTIVE

The incidence of labor induction is rising rapidly in the United States. Among multiparas, labor is often followed with traditional labor curves derived from noninduced pregnancies. We sought to determine how labor progression of multiparous women who presented in spontaneous labor differed from those who were electively induced with and from those induced without preinduction cervical ripening.

METHODS

We analyzed data on all low-risk multiparous women with an elective induction or spontaneous onset of labor between 37(+0) and 40(+6) weeks of gestation from January 2002 to March 2004 at a single institution. The median duration of labor by each centimeter of cervical dilatation and the risk of cesarean delivery were computed for 61 women with preinduction cervical ripening and oxytocin induction, 735 women with oxytocin induction, and 1,885 women with a spontaneous onset of labor. An intracervical Foley catheter was used to ripen the cervix.

RESULTS

Those women who experienced electively induced labor without cervical ripening had a shorter active phase of labor than did those admitted in spontaneous labor (99 minutes in induced labor versus 161 minutes in spontaneous labor, P < .001). However, the cesarean delivery rate was elevated in the induction group (3.9% versus 2.3%, P < .05). Women who underwent preinduction cervical ripening also had a shorter active phase than those admitted in spontaneous labor (109 minutes versus 161 minutes, P = .01).

CONCLUSION

The pattern of labor progression differs for women with an electively induced labor without cervical ripening compared with those who present with spontaneous onset of labor.

Hyaluronidase for cervical ripening and induction of labour

BACKGROUND

Dilatation and effacement of the cervix are not only a result of uterine contractions, but are also dependent upon ripening processes within the cervix. The cervix is a fibrous organ composed principally of hyaluronic acid, collagen and proteoglycan. Hyaluronic acid increases markedly after the onset of labour. An increase in the level of hyaluronic acid is associated with an increase in tissue water content. Cervical ripening during labour is characterised by changes of the cervix and an increased water content. Cervical injection of hyaluronidase was postulated to increase cervical ripening. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of hyaluronidase for third trimester cervical ripening or induction of labour in comparison with other methods of induction of labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2006) and bibliographies of relevant papers.

SELECTION CRITERIA

Clinical trials of hyaluronidase for third trimester cervical ripening or labour induction.

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. We assessed trial quality. We contacted study authors for additional information. We collected adverse effects information from the trials.

MAIN RESULTS

One trial, with 168 women participating, was included in the review. When compared with placebo for cervical ripening intracervical injections of hyaluronidase resulted in women receiving significantly fewer caesarean sections (18% versus 49%, relative risk (RR) 0.37, 95% confidence interval (CI) 0.22 to 0.61), less need for oxytocin augmentation (10% versus 47%, RR 0.20, 95% CI 0.10 to 0.41), and increased cervical favourability after 24 hours (60% versus 98%, RR 0.62, 95% CI 0.52 to 0.74). No side-effects for mother or baby were reported in this trial.

AUTHORS' CONCLUSIONS

Intracervical injections of hyaluronidase for cervical ripening appear beneficial. However, this is not common practice. In addition it is an invasive procedure that women may find unacceptable in the presence of less invasive methods.

Corticosteroids for cervical ripening and induction of labour

BACKGROUND

The role of corticosteroids in the process of labour is not well understood. Animal studies have shown the importance of cortisol secretion by the fetal adrenal gland in initiating labour in sheep. Infusion of glucocorticosteroids into the fetus has also shown to induce premature labour in sheep. Given these studies it has been postulated that corticosteroids will promote the induction of labour in women. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of corticosteroids for third trimester cervical ripening or induction of labour in comparison with other methods of cervical priming or induction of labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005) and bibliographies of relevant papers.

SELECTION CRITERIA

Clinical trials of corticosteroids for third trimester cervical ripening or labour induction.

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. We assessed trial quality. We contacted study authors for additional information. We collected adverse effects information from the trials.

MAIN RESULTS

Only one small trial (66 women) was included. The primary outcome vaginal birth within 24 hours was not reported. No benefit of intramuscular administration of corticosteroids with intravenous oxytocin was found when compared with oxytocin alone. However, given the small size of this trial this result should be interpreted cautiously.

AUTHORS' CONCLUSIONS

The effectiveness of corticosteroids for induction of labour is uncertain. This method of induction of labour is not commonly used and so further research in this area is probably unwarranted.

[Transvaginal ultrasound assessment of the cervix and digital examination before labor induction]

OBJECTIVE

To examine the relationship between sonographic measurement of cervical length and Bishop score with duration of labour induction.

METHODS

A prospective, blinded, observational study was performed in 191 pregnant women undergoing labor induction. Ultrasound measurement of cervical length and determination of Bishop score were performed. Induction was based exclusively on the Bishop score according to Obstetric Unit protocol. The criteria for considering the cervix unripe were either Bishop score < 6 or a cervical length = 26 mm. Duration of induction is defined like the induction-to-delivery interval. The main outcomes assessed were the duration of induction, the delivery within 24 h of induction and type of delivery.

RESULTS

The duration of induction was between 2 h 27 min and 61 h 30 min. We found an association between cervical length and Bishop score with duration of induction. The duration of induction was significantly increased in nulliparous (median 18 h 38 min vs. 9 h 18 min). There was no correlation of age or weight of pregnant women with the duration of induction. Comparison between Bishop score and cervical length in predicting delivery within the first 24 hours showed that the pregnant women with low Bishop score had a higher risk of deliver after 24 hours of induction (OR = 21.16), as the ones with cervical length longer than 26 mm (OR = 5.06). Analyzing the relation of these two parameters with type of delivery we realize that low Bishop score has a higher risk of cesarean section (OR = 2.67) and that there wasn't any relation between type of delivery and cervical length.

DISCUSSION

In this study we verified a statistically significant relation between Bishop score, US cervical length and previous vaginal birth with induction duration. Pregnant woman's age and weight didn't have influence on the duration of induction. The study showed that both Bishop score and US cervical length are useful in predicting delivery within the first 24 hours. Bishop score was also related with type of delivery.