Duration of labor induction in nulliparous women at term: how long is long enough?

An Externally Validated Model to Predict Prolonged Induction of Labor with an Unfavorable Cervix

OBJECTIVE

 To develop and externally validate a prediction model to calculate the likelihood of prolonged induction of labor (induction start to delivery time > 36 hours).

STUDY DESIGN

 This was a retrospective cohort study of all nulliparous women with singleton pregnancies and vertex presentation at term who underwent induction of labor and had a vaginal delivery at a single academic center. Women with contraindications for vaginal delivery were excluded. Analyses were limited to women with unfavorable cervix (both simplified Bishop score [dilation, station, and effacement: range 0-9] <6 and cervical dilation <3 cm). Prolonged induction of labor was defined as the duration of induction (induction start time to delivery) longer than 36 hours. A backward stepwise logistic regression analysis was used to identify the factors associated with prolonged induction of labor by considering maternal characteristics and comorbidities as well as fetal conditions. The final model was validated using an external dataset of the Consortium on Safe Labor after applying the same inclusion and exclusion criteria. We developed a receiver observer characteristic curve with area under the curve (AUC) in validation cohorts.

RESULTS

 Of 2,118 women, 364 (17%) had prolonged induction of labor. Factors associated with prolonged induction of labor included body mass index at admission, hypertension, fetal conditions, and epidural. Factors including younger maternal age, prelabor rupture of membranes, and a more favorable simplified Bishop score were associated with a decreased likelihood of prolonged induction of labor. In the external validation cohort, 4,418 women were analyzed, of whom 188 (4%) had prolonged induction of labor. The AUC of the final model was 0.76 (95% confidence interval: 0.73-0.80) for the external validation cohort. The online calculator was created and is available at: https://medstarapps.org/obstetricriskcalculator.

CONCLUSION

 Our externally validated model was efficient in predicting prolonged induction of labor with an unfavorable cervix.

KEY POINTS

· The number of inductions of labor at 39 weeks' gestation and beyond has been increasing.. · Our model had a good prediction of prolonged induction of labor.. · An online calculator has been created and available..

Change in timing of induction protocol in nulliparous women to optimise timing of birth: results from a single centre study

BACKGROUND

Induction of labour (IOL) is a common obstetric intervention. When planning IOL, especially in women at risk for complications at delivery, the aim should be for delivery to occur when senior staff are available to optimise safe care.

METHODS

A change in timing of IOL protocol at our institution was introduced in November 2018 aiming to increase births occurring "in-hours" defined as 08:00 to 20:00 h. This retrospective cohort study compares the odds of "in-hours" birth before and after the intervention and the association on birth outcomes. The study compared outcomes during the new IOL pathway period to a historical birth cohort from January to December 2017. Inclusion criteria were nulliparous women undergoing planned IOL at term with a cephalic singleton pregnancy. Logistic regression was used to compare odds of in-hours birth for the 2 periods with adjustment for maternal age at delivery, gestation, more than 2 cervical ripening agents required, undergoing IOL for post-dates pregnancy, mode of birth, whether or not IOL proceeded according to planned protocol and missing values using multiple imputation.

RESULTS

The rate of deliveries occurring in-hours were higher following the intervention; n = 118/285 (45.6%) pre-intervention versus n = 251/470 (53.4%) post-intervention; adjusted OR = 1.47, 95% CI = 1.07-2.01, p = 0.02). The percentage of caesarean sections (CS) occurring in-hours was significantly lower in the pre-intervention group n = 71/153 (28.3%) compared with the post intervention group = 35/132(46.4%) (p < 0.001)). The rate of CS was higher in the pre intervention n = 132/285(46.3%) compared with the post intervention group n = 153/470 (32.4%)).

CONCLUSIONS

The change in induction procedures was associated with a significantly higher rate of births occurring in-hours and a lower rate of overall of CS. This policy change led to a better pattern of timing of birth for nulliparous women undergoing IOL.

A double-blinded randomized controlled trial on the effects of increased intravenous hydration in nulliparas undergoing induction of labor

BACKGROUND

Rates of labor induction are increasing, raising concerns related to increased healthcare utilization costs. High-dose intravenous fluid (250 cc/h) has been previously demonstrated to shorten the time to delivery in nulliparous individuals in spontaneous labor. Whether or not this relationship exists among individuals undergoing induction of labor is unknown.

OBJECTIVE

Our study aimed to evaluate the effect of high-dose intravenous hydration on time to delivery among nulliparous individuals undergoing induction of labor.

STUDY DESIGN

Nulliparous individuals presenting for induction of labor with a Bishop score of ≤6 (with and without rupture of membranes) were randomized to receive either 125 cc/h or 250 cc/h of normal saline. The primary outcome was length of labor (defined as time from initiation of study fluids to delivery). Both time to overall delivery and vaginal delivery were evaluated. Secondary outcomes included the lengths of each stage of labor, the percentage of individuals delivering within 24 hours, and maternal and neonatal outcomes, including cesarean delivery rate.

RESULTS

A total of 180 individuals meeting inclusion criteria were enrolled and randomized. Baseline demographic characteristics were similar between groups; however, there was a higher incidence of diabetes mellitus in the group receiving 125 cc/h. Average length of labor was similar between groups (27.6 hours in 250 cc/h and 27.8 hours in 125 cc/h), as was the length of each stage of labor. Cox regression analysis did not demonstrate an effect of fluid rate on time to delivery. Neither the admission Bishop score, body mass index, nor other demographic characteristics affected time to delivery or vaginal delivery. There were no differences in maternal or neonatal outcomes, including overall cesarean delivery rate, clinically apparent iatrogenic intraamniotic infection, Apgar scores, need for neonatal phototherapy, or neonatal intensive care unit stay.

CONCLUSION

There were no observed differences in the length of labor or maternal or neonatal outcomes with the administration of an increased rate of intravenous fluids among nulliparous individuals undergoing induction of labor.

Out-of-Hospital Cervical Ripening With a Synthetic Hygroscopic Cervical Dilator May Reduce Hospital Costs and Cesarean Sections in the United States-A Cost-Consequence Analysis

Objective: Out-of-hospital (outpatient) cervical ripening prior to induction of labor (IOL) is discussed for its potential to decrease the burden on hospital resources. We assessed the cost and clinical outcomes of adopting an outpatient strategy with a synthetic hygroscopic cervical dilator, which is indicated for use in preinduction cervical ripening.

Methods: We developed a cost-consequence model from the hospital perspective with a time period from IOL to post-delivery discharge. A hypothetical cohort of women to undergo IOL at term with an unfavorable cervix (all risk levels) were assessed. As the standard of care (referred to as IP-only) all women were ripened as inpatients using the vaginal PGE2 insert or the single-balloon catheter. In the comparison (OP-select), 50.9% of low-risk women (41.4% of the study population) received outpatient cervical ripening using a synthetic hygroscopic cervical dilator and the remaining women were ripened as inpatients as in the standard of care. Model inputs were sourced from a structured literature review of peer-reviewed articles in PubMed. Testing of 2,000 feasible scenarios (probabilistic multivariate sensitivity analysis) ascertained the robustness of results. Outcomes are reported as the average over all women assessed, comparing OP-select to IP-only.

Results: Implementing OP-select resulted in hospital savings of US$689 per delivery, with women spending 1.48 h less time in the labor and delivery unit and 0.91 h less in the postpartum recovery unit. The cesarean-section rate was decreased by 3.78 percentage points (23.28% decreased to 19.50%). In sensitivity testing, hospital costs and cesarean-section rate were reduced in 91% of all instances.

Conclusion: Our model analysis projects that outpatient cervical ripening has the potential to reduce hospital costs, hospital stay, and the cesarean section rate. It may potentially allow for better infection-prevention control during the ongoing COVID-19 pandemic and to free up resources such that more women might be offered elective IOL at 39 weeks.

Vaginal streptococcus B colonization is not associated with increased infectious morbidity in labor induction

INTRODUCTION

Labor induction rates are increasing and, in Finland today, one of three labors is induced. Group B streptococcus (GBS) is a bacterium found in 10%-30% of pregnant women and it can be transmitted to the neonate during vaginal delivery. Although GBS is rarely harmful in the general population, it is the leading cause of severe neonatal infections such as sepsis, pneumonia, and meningitis. In addition, GBS can cause maternal morbidity. Labor induction in GBS-positive women has not yet been investigated but concerns of infectious morbidity associated with balloon catheters have been raised.

MATERIAL AND METHODS

A historical cohort study of 1959 women undergoing labor induction by balloon catheter in Helsinki University Hospital, Finland, between January 1, 2014 and December 31, 2017. Women with viable singleton term pregnancy in cephalic presentation, unfavorable cervix (Bishop score <6), and intact amniotic membranes were included. GBS was screened by rapid qualitative in vitro test (XPert^® GBS) from vaginal and perineal culture upon admission for labor induction. All women testing positive received prophylactic antibiotics.

RESULTS

Of the women, 469 (23.9%) were GBS-positive. The rate of maternal intrapartum infection was 7.4%, being lower in the GBS-positive group compared with the GBS-negative group (4.7% vs 8.3%; p = 0.01). The rate of maternal postpartum infection was 3.9%, and the rate of neonatal infection was 3.3%, both being similar between the groups. Also, no difference in the rates of other adverse neonatal outcomes was seen. No GBS sepses occurred in the study. In multivariable logistic regression, rupture of membranes to delivery interval ≥12 hours was associated with maternal intrapartum and postpartum infection, as well as neonatal infection. Other risk factors for maternal intrapartum infection were GBS-negativity, nulliparity, prolonged pregnancy (≥41 weeks), and Bishop score <3 at the start of induction. Cesarean section was associated with postpartum endometritis, while nulliparity, gestational diabetes, and maternal intrapartum infection were associated with neonatal infection.

CONCLUSIONS

Regarding maternal and neonatal infectious morbidity, labor induction with balloon catheter appears safe in women colonized with GBS when prophylactic antibiotics are administered at the onset of labor or at membrane rupture.

Inpatient versus outpatient induction of labour: a systematic review and meta-analysis

Background

As the number of indications for labour induction continue to increase, the focus has shifted to performing these procedures in an outpatient setting. This study aims to systematically review published data from randomized controlled trials that compare outpatient with inpatient labour induction, to ascertain the role of outpatient labour induction for low-risk pregnancies.

Methods

We conducted a systematic review wherein we searched MEDLINE, EMBASE, Biosis Previews®, and International Pharmaceutical Abstracts from inception to January 2020 to identify randomized controlled trials that reported on maternal, fetal and resource-related outcomes following outpatient versus inpatient labour induction. Pooled incidences and mean differences were calculated using random-effects meta-analysis. Risk-of-bias was assessed using the Cochrane Risk of Bias tool. Subgroup analysis was conducted based on the method of induction.

Results

Of the 588 records identified, 12 publications, representing nine independent randomized controlled trials conducted in Australia, Europe and North America, were included. These reported on 2615 cases of labour induction (1320 outpatients versus 1295 inpatients). Overall, apart from a higher number of suspicious fetal heart rate tracings [RR = 1.43 (1.10, 1.86)] and a shorter mean length of hospital stay [MD = 282.48 min (160.23, 404.73) shorter] in the outpatient group, there were no differences in delivery method, adverse outcomes or resource-use between the two arms. On subgroup analysis, when comparing the use of balloon catheters in both arms, those induced as outpatients had fewer caesarean deliveries [RR = 0.52 (0.30, 0.90)], a shorter admission-to-delivery interval [MD = 370.86 min (19.19, 722.54) shorter], and a shorter induction to delivery interval [MD = 330.42 min (120.13, 540.71) shorter].

Conclusion

Outpatient labour induction in resource-rich settings is at least as effective and safe, in carefully selected patient populations, when compared with inpatient labour induction. Whether outpatient labour induction results in lower rates of caesarean deliveries needs to be explored further.

Trial registration

This systematic review was prospectively registered in Prospero (CRD42019118049).

PROMOTE Study: Safety of Osteopathic Manipulative Treatment During the Third Trimester by Labor and Delivery Outcomes

BACKGROUND

Few quality data exist on the safety of osteopathic manipulative treatment (OMT) during pregnancy. The Pregnancy Research on Osteopathic Manipulation Optimizing Treatment Effects (PROMOTE) study was a randomized controlled clinical trial that studied the application of an OMT protocol to manage pain and dysfunction in pregnant patients during their third trimester.

OBJECTIVE

To evaluate the safety of an OMT protocol applied during the third trimester of pregnancy by analyzing incidence of high-risk status and labor and delivery outcomes.

METHODS

In the PROMOTE study, 400 pregnant patients were randomly assigned to 1 of 3 study groups: usual care plus OMT (OMT), usual care plus placebo ultrasound treatment (PUT), or usual care only (UCO). The incidence of high-risk status of participants and outcomes of labor and delivery, including length of labor, fever in mother during labor, operative vaginal delivery, conversion to cesarean delivery, need for forceps or vacuum device, need for episiotomy, incidence of perineal laceration, meconium-stained amniotic fluid, and infants' Apgar scores, were analyzed.

RESULTS

Data from 380 participants were studied. High-risk status was less likely to develop in participants who received OMT (95% CI, 0.16-0.91; P=.03). The OMT protocol also did not increase risk of precipitous labor, operative vaginal delivery, conversion to cesarean delivery, need for forceps or vacuum device, need for episiotomy, incidence of perineal laceration, or meconium-stained amniotic fluid when compared with participants in the other 2 groups (P>.05). Of all other maternal outcomes examined, no difference was reported among the 3 treatment groups with the exception of incidence of prolonged labor in the OMT group. Participants receiving OMT had longer durations of labor than participants in the other groups (P=.002).

CONCLUSION

These results suggest that the OMT protocol given during the third trimester of pregnancy as applied in the PROMOTE study is safe with regard to labor and delivery outcomes. The increased duration in labor in the OMT group needs further study. (ClinicalTrials.gov number NCT00426244).

Cesarean delivery among women with prolonged labor induction

OBJECTIVE

The objective of this study was to determine characteristics associated with cesarean delivery among women with labor induction lasting over 24 h.

STUDY DESIGN

Women with live singleton pregnancies without prior cesarean delivery undergoing a labor induction lasting >24 h between September 2006 and March 2009 at Duke University Hospital were identified. Collected variables were compared between subjects by mode of delivery. A multivariate logistic regression model for the outcome cesarean delivery was constructed separately for nulliparous and parous women.

RESULTS

There were 303 women who met inclusion criteria. The overall cesarean delivery rate was 57% (n=172) and remained constant with time (P=0.15, test-for-trend). Nulliparous women having a cesarean delivery were more likely to be obese [adjusted OR (aOR) 2.00; 95% CI 1.05, 3.80] and have a larger fetus [aOR 1.11 (aOR for every 100 g increase in birthweight), 95% CI 1.03, 1.20] compared to those having a vaginal delivery.

CONCLUSION

Increasing BMI and birthweight were independent predictors of cesarean delivery among nulliparous women with prolonged labor induction. Despite this, after 24 h of labor induction, the overall mean cesarean delivery rate remained constant at 57%, and did not change with time. Among women having a vaginal delivery following a prolonged labor induction, we saw high rates of shoulder dystocia, operative vaginal delivery and severe perineal laceration.

Failed labor induction: toward an objective diagnosis

OBJECTIVE

To evaluate maternal and perinatal outcomes in women undergoing labor induction with an unfavorable cervix according to duration of oxytocin administration in the latent phase of labor after ruptured membranes.

METHODS

This was a secondary analysis of a randomized multicenter trial in which all cervical examinations from admission were recorded.

INCLUSION CRITERIA

nulliparas at or beyond 36 weeks of gestation undergoing induction with a cervix of 2 cm or less dilated and less than completely effaced. The latent phase of labor was defined as ending at a cervical dilation of 4 cm and effacement of at least 90%, or at a cervical dilation of 5 cm regardless of effacement.

RESULTS

A total of 1,347 women were analyzed. The overall vaginal delivery rate was 63.2%. Most women had exited the latent phase after 6 hours of oxytocin and membrane rupture (n=939; 69.7%); only 5% remained in the latent phase after 12 hours. The longer the latent phase, the lower the vaginal delivery rate. Even so, 39.4% of the 71 women who remained in the latent phase after 12 hours of oxytocin and membrane rupture were delivered vaginally. Chorioamnionitis, endometritis, or both, and uterine atony were the only maternal adverse outcomes related to latent-phase duration: adjusted odds ratios (95% confidence intervals) of 1.12 (1.07, 1.17) and 1.13 (1.06, 1.19), respectively, for each additional hour. Neonatal outcomes were not related to latent-phase duration.

CONCLUSION

Almost 40% of the women who remained in the latent phase after 12 hours of oxytocin and membrane rupture were delivered vaginally. Therefore, it is reasonable to avoid deeming labor induction a failure in the latent phase until oxytocin has been administered for at least 12 hours after membrane rupture.

LEVEL OF EVIDENCE

III.

Intrapartum considerations in prenatal care

The epidemic of obesity continues to grow undaunted, promising to affect the lives of more women of childbearing age. The challenges facing those charged with obstetrical care of the obese may require variation in care from forethought and planning, to consultation or referral for care at specialized centers. The routine management of late pregnancy must take into account the increase in risk for late fetal loss, failed induction and trial of labor after cesarean delivery, and postcesarean complications, such as wound-related morbidity and venous thromboembolism. Awareness of prolonged labor curves and the risk of shoulder dystocia must also be part of the management of labor. The data regarding many interventions attempted on behalf of these at risk gravidas are rudimentary but may allow for modifications in care that will positively impact outcomes for mother and child.

Intrauterine bacterial growth at birth and risk of asthma and allergic sensitization among offspring at the age of 15 to 17 years

BACKGROUND

Microbial colonization of the airways and intestine during birth might have an effect on the risk of asthma and allergic diseases later in life.

OBJECTIVE

We sought to evaluate the association between intrauterine microbial growth at the time of delivery and the development of asthma and allergic sensitization among offspring.

METHODS

Intrauterine bacterial culture results were recorded at the time of cesarean delivery of 460 children who were born at Kuopio University Hospital during 1990-1992. When the children reached the age of 15 to 17 years, self-administered questionnaires were sent to the mothers, and 382 of the children were also examined by using skin prick tests.

RESULTS

Intrauterine growth of potential pathogenic anaerobic bacteria and Streptococcus species at birth was associated with an increased risk of doctor-diagnosed asthma ever (odds ratio [OR], 4.51 [95% CI, 1.56-13.0]; OR, 2.53 [95% CI, 1.19-5.38]) and doctor-diagnosed current asthma (OR, 7.34 [95% CI, 2.44-22.03]; OR, 3.37 [95% CI, 1.46-7.76]) at the age of 15 to 17 years compared with the risk seen in subjects with negative microbial cultures. These findings remained significant also after applying the Bonferroni correction. No significant association after the Bonferroni correction was detected between intrauterine microbial growth and allergic sensitization among offspring.

CONCLUSION

The results of this study indicated that specific intrauterine microbial growth at the time of birth might increase the risk of asthma among offspring through inflammatory mechanisms. These results indicate new potential targets for future studies on the effects of maternal vaginal microflora and intrauterine infection in the development of asthma among children.

Overestimation of fetal weight by ultrasound: does it influence the likelihood of cesarean delivery for labor arrest?

OBJECTIVE

We sought to determine whether the overestimation of ultrasound-derived estimated fetal weight (EFW) is associated with increased diagnosis of labor arrest.

STUDY DESIGN

This is a historical cohort study of nulliparous women with term pregnancies who underwent bedside ultrasound examination for EFW before labor induction. Labor outcomes of women with EFW overestimation > 15% the actual birthweight were compared with those with EFW not overestimated.

RESULTS

Overestimation of EFW occurred in 9.5% of cases (23/241). The rate of cesarean delivery (CD) for labor arrest was higher for those with EFW overestimation (34.8% vs 13.3%; P = .01) even though there were no differences in length of the induction duration. After adjusting for confounding factors, EFW overestimation remained associated with CD for labor arrest (odds ratio, 4.8; 95% confidence interval, 1.5-15.2).

CONCLUSION

Our finding suggests that an overestimation of EFW may be associated with a lower threshold for CD for labor arrest.

Cesarean delivery for abnormal labor

Cesarean delivery is indicated at any stage in the labor process in the presence of nonreassuring fetal status or when conservative measures fail in the setting of abnormal labor. In the absence of maternal or fetal indications for expedited delivery, cesarean delivery is not indicated for latent phase disorders. When to intervene for protracted labor is arguable, but slow rates of labor progress are consistent with safe vaginal delivery. Cesarean delivery in the second stage should be avoided for at least 4 hours if there is progressive fetal descent.