Routine induction of labour at 41 weeks gestation: nonsensus consensus

Validation and factor structure of the Italian version of the Birth Satisfaction Scale-Revised (BSS-R)

OBJECTIVE

To validate the Italian-language version of the Birth Satisfaction Scale-Revised (BSS-R) and report key measurement properties of the tool. To evaluate the impact of antenatal class attendance on BSS-R assessed birth satisfaction.

BACKGROUND

Maternal satisfaction is one of the standards of care defined by the World Health Organisation (WHO) to improve the quality of services. The BSS-R is a multi-dimensional self-report measure of the experience of labour and birth.

METHODS

Cross-sectional instrument evaluation design examining factor structure and key aspects of validity and reliability. Embedded between-subjects design to examine known-group discriminant validity and the impact of antenatal class attendance on BSS-R sub-scale and total scores as dependent variables. After giving birth, 297 women provided data for analysis.

RESULTS

The Italian version of the BSS-R (I-BSS-R) was the key study measure. The established three-factor and bi-factor models of the BSS-R were found to offer an excellent fit to the data. Comparison of the tri-dimensional measurement model and the bi-factor model of the BSS-R found no significant differences between models. Women who attended antenatal classes had significantly lower stress experienced during childbearing sub-scale scores (I-BSS-R SE), compared to those who did not. Good convergent, divergent validity and known-groups discriminant validity were established for the I-BSS-R. Internal consistency observations were found to be sub-optimal in this population.

CONCLUSIONS

On all key psychometric indices, with the exception of internal consistency that requires further investigation, the I-BSS-R was found to be a valid translation of the original BSS-R. The impact of antenatal classes on birth satisfaction warrants further research.

No. 214-Guidelines for the Management of Pregnancy at 41+0 to 42+0 Weeks

OBJECTIVE

To provide evidence-based guidelines for the management of pregnancy at 41+0 to 42+0 weeks.

OUTCOMES

Reduction of perinatal mortality associated with Caesarean section at 41+0 to 42+0 weeks of pregnancy.

EVIDENCE

The Medline database, the Cochrane Library, and the American College of Obstetricians and Gynecologists and the Royal College of Obstetricians and Gynecologists, were searched for English language articles published between 1966 and March 2007, using the following key words: prolonged pregnancy, post-term pregnancy, and postdates pregnancy. The quality of evidence was evaluated and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care.

RECOMMENDATIONS

Does a policy of earlier induction affect labour outcomes in women induced for postmaturity? A retrospective analysis in a tertiary hospital in the North of England

OBJECTIVES

to investigate whether a change in the management of postmature pregnancy to earlier induction affects the length of labour and the induction process. Secondly, to assess the feasibility of the research process to inform a future larger study.

DESIGN

a change in management of postmature pregnancy in an NHS hospital in October 2013, from induction at 42 weeks gestation to induction between 41-42 weeks, provided an opportunity to conduct a retrospective analysis. Pre-existing data from the maternity database and casenotes were collected and primary outcomes analysed using the Mann-Whitney test and the Hodges-Lehman confidence interval for differences in medians.

SETTING

a large city based tertiary referral hospital in the North of England.

PARTICIPANTS

125 women induced before the change in policy were compared with 309 women induced after the change.

MEASUREMENTS

primary outcomes were length of 1st and 2nd stage of labour, overall length of labour, length of induction to established labour and length of induction to birth.

FINDINGS

the median overall length of labour for women induced at 42 weeks was 6.5hours, while for women induced at 41-42 weeks this was 5.2hours. The difference was not statistically significant (p=0.15, 95% CI for median difference -0.27 to 1.93hours) with a small effect size (Pearson's r=-0.08). The median length of induction to birth was 13.6hours for women induced at 42 weeks and 16.5hours for women induced at 41-42 weeks. This difference was also not statistically significant (p=0.14, 95% CI for median difference -7.25 to 1.20hours) with a small effect size (Pearson's r=-0.13).

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

This study demonstrated no statistically significant differences in length of labour and induction following a change in the management of postmature pregnancy to earlier induction. A large study is needed to establish definitively the effects of earlier induction on labour outcomes.

Dueling Statistics: Is Out-of-Hospital Birth Safe?

In this article, two recent studies comparing out-of-hospital birth and hospital birth are discussed. The author critiques the studies highlighting the possible reasons for differences in the findings related to home birth. In addition, the findings of both studies add to the body of knowledge that suggests there are risks associated with hospital birth.

Asphyxia, Neurologic Morbidity, and Perinatal Mortality in Early-Term and Postterm Birth

BACKGROUND AND OBJECTIVES

Neonatal outcomes vary by gestational age. We evaluated the association of early-term, full-term, and postterm birth with asphyxia, neurologic morbidity, and perinatal mortality.

METHODS

Our register-based study used retrospective data on 214 465 early-term (37(+0)-38(+6) gestational weeks), 859 827 full-term (39(+0)-41(+6)), and 55 189 postterm (≥42(+0)) live-born singletons during 1989-2008 in Finland. Asphyxia parameters were umbilical cord pH and Apgar score at 1 and 5 minutes. Neurologic morbidity outcome measures were cerebral palsy (CP), epilepsy, intellectual disability, and sensorineural defects diagnosed by the age of 4 years. Newborns with major congenital anomalies were excluded from perinatal deaths.

RESULTS

Multivariate analysis showed that, compared with full-term pregnancies, early-term birth increased the risk for low Apgar score (<4) at 1 and 5 minutes (odds ratio 1.03, 95% confidence interval 1.03-1.04 and 1.24, 1.04-1.49, respectively), CP (1.40, 1.27-1.55), epilepsy (1.14, 1.06-1.23), intellectual disability (1.39, 1.27-1.53), sensorineural defects (1.24, 1.17-1.31), and perinatal mortality (2.40, 2.14-2.69), but risk for low umbilical artery pH ≤7.10 was decreased (0.83, 0.79-0.87). Postterm birth increased the risk for low Apgar score (<4) at 1 minute (1.26, 1.26-1.26) and 5 minutes (1.80, 1.43-2.34), low umbilical artery pH ≤7.10 (1.26, 1.19-1.34), and intellectual disability (1.19, 1.00-1.43), whereas risks for CP (1.03, 0.84-1.26), epilepsy (1.00, 0.87-1.15), sensorineural defects (0.96, 0.86-1.07), and perinatal mortality (0.91, 0.69-1.22) were not increased.

CONCLUSIONS

Early-term birth was associated with low Apgar score, increased neurologic morbidity, and perinatal mortality. Asphyxia and intellectual disability were more common among postterm births, but general neurologic morbidity and perinatal mortality were not increased.

Using inter-institutional practice variation to understand the risks and benefits of routine labour induction at 41(+0) weeks

OBJECTIVE

To evaluate the risks and benefits of routine labour induction at 41(+0) weeks' gestation for mother and newborn.

DESIGN

Population-based retrospective cohort study of inter-institutional variation in labour induction practices for women at or beyond 41(+0) weeks' gestation.

POPULATION

Women in British Columbia, Canada, who remained pregnant ≥41(+0) weeks and delivered at one of the province's 42 hospitals with >50 annual deliveries, 2008-2012 (n = 14,627).

METHODS

The proportion of women remaining pregnant a week or more past the expected delivery date who were induced at 41(+0) or 41(+1) weeks' gestation for an indication of 'post-dates' was calculated for each institution. We used instrumental variable analysis (using the institutional rate of labour induction at 41(+0) weeks as the instrument) to estimate the effect of labour induction on maternal and neonatal health outcomes.

MAIN OUTCOME MEASURES

Caesarean delivery, instrumental delivery, post-partum haemorrhage, 3rd or 4th degree lacerations, macrosomia, neonatal intensive care unit admission, and 5-minute Apgar score <7.

RESULTS

Institutional rates of labour induction at 41(+0) weeks ranged from 14.3 to 46%. Institutions with higher (≥30%) and average (20-29.9%) induction rates did not have significantly different rates of caesarean delivery, instrumental delivery, or other maternal or neonatal outcomes than institutions with lower induction rates (<20%). Instrumental variable analyses also demonstrated no significantly increased (or decreased) risk of caesarean delivery (0.69 excess cases per 100 pregnancies [95% CI -10.1, 11.5]), instrumental delivery (8.9 per 100 [95% CI -2.3, 20.2]), or other maternal or neonatal outcomes in women who were induced (versus not induced).

CONCLUSIONS

Within the current range of clinical practice, there was no evidence that differential use of routine induction at 41(+0) weeks affected maternal or neonatal health outcomes.

Comparison effect of oral propranolol and oxytocin versus oxytocin only on induction of labour in nulliparous women (a double blind randomized trial)

BACKGROUND AND AIM

Today, research on new methods for preventing caesarean sections owing to labour induction, have been requested in obstetric practice, because of the increased morbidity related to caesarean section. Therefore, the aim of this study was to compare the effect of Oral Propranolol and Oxytocin versus Oxytocin only on induction of labour in nulliparous women.

MATERIAL AND METHODS

A double blind randomized controlled trial was performed at the Ilam Mostafa Hospital, Ilam, Iran, from March 2010 to March 2011 on 146 nulliparous pregnant women who had gestational age of 40-42 weeks of pregnancy and a Bishop score of ≤5. Participants were divided in two groups (with 73 participants in each group). In the first group (placebo plus Oxytocin group = 73), Oxytocin was used for the induction of labour. In the second group (Propranolol plus Oxytocin group = 73 cases), before the use of Oxytocin, 20 mg Propranolol was administrated orally and then the Oxytocin was initiated. Twenty mg Propranolol was repeated after 8 hours if good contraction was not obtained.

RESULTS

The mean duration for obtaining good contractions was significantly shorter in the Propranolol group than in the placebo group, on both the first and second day of induction (p<.05). The mean duration of latent phase was shorter in the first in Propranolol group (p<.05). In Propranolol plus Oxytocine group, frequency of cesarean deliveries significantly decreased than in the placebo plus Oxytocin group (21% versus 39.7%). No significant differences in neonate outcome, such as Apgar scores of minutes 1 and 5 and need of admissions to NICU, were found between the groups (p>.05) DISCUSSION AND CONCLUSION: Our study showed that oral Propranolol was effective for labour induction and that it could decrease the frequency of caesarean deliveries without producing any adverse effects on mothers or neonates.

Does induction of labour increase the risk of caesarean section? A systematic review and meta-analysis of trials in women with intact membranes

BACKGROUND

Recent literature on the effect of induction of labour (compared with expectant management) has provided conflicting results. Reviews of observational studies generally report an increase in the rate of caesarean section, whereas reviews of post-dates and term prelabour rupture of membrane (PROM trials suggest either no difference or a reduction in risk.

OBJECTIVE

To evaluate with a systematic review and meta-analysis of randomised controlled trials (RCTs) whether or not the induction of labour increases the risk of caesarean section in women with intact membranes.

SEARCH STRATEGY

Literature search using electronic databases: MEDLINE, EMBASE, and the Cochrane Database of Clinical Trials.

SELECTION CRITERIA

RCTs comparing a policy of induction of labour with expectant management in women with intact membranes.

DATA COLLECTION AND ANALYSIS

A total of 37 trials were identified and reviewed. Quantitative analyses with fixed- and random-effects models were performed with revman 5.1.

MAIN RESULTS

Of the 37 RCTs, 27 were trials of uncomplicated pregnancies at 37-42 weeks of gestation. The remaining ten evaluated induction versus expectant management in pregnancies with suspected macrosomia (two), diabetes in pregnancy (one), oligohydramnios (one), twins (two), intrauterine growth restriction (IUGR) (two), mild pregnancy-induced hypertension (PIH) (one), and women with a high-risk score for caesarean section (one). Meta-analysis of 31 trials determined that a policy of induction was associated with a reduction in the risk of caesarean section compared with expectant management (OR 0.83, 95% CI 0.76-0.92).

AUTHOR'S CONCLUSIONS

Induction of labour in women with intact membranes reduces the risk of caesarean section. Review of the trials suggests that this effect may arise from non-treatment effects, and that additional trials are needed.

Induction of labour for improving birth outcomes for women at or beyond term

BACKGROUND

As a pregnancy continues beyond term the risks of babies dying inside the womb or in the immediate newborn period increase. Whether a policy of labour induction at a predetermined gestational age can reduce this increased risk is the subject of this review.

OBJECTIVES

To evaluate the benefits and harms of a policy of labour induction at term or post-term compared with awaiting spontaneous labour or later induction of labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2012).

SELECTION CRITERIA

Randomised controlled trials conducted in women at or beyond term. The eligible trials were those comparing a policy of labour induction with a policy of awaiting spontaneous onset of labour. Cluster-randomised trials and cross-over trials are not included. Quasi-random allocation schemes such as alternation, case record numbers or open random-number lists were not eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion. Two review authors independently assessed trial quality and extracted data. Data were checked for accuracy. Outcomes are analysed in two main categories: gestational age and cervix status.

MAIN RESULTS

We included 22 trials reporting on 9383 women. The trials were generally at moderate risk of bias.Compared with a policy of expectant management, a policy of labour induction was associated with fewer (all-cause) perinatal deaths: risk ratio (RR) 0.31, 95% confidence interval (CI) 0.12 to 0.88; 17 trials, 7407 women. There was one perinatal death in the labour induction policy group compared with 13 perinatal deaths in the expectant management group. The number needed to treat to benefit (NNTB) with induction of labour in order to prevent one perinatal death was 410 (95% CI 322 to 1492).For the primary outcome of perinatal death and most other outcomes, no differences between timing of induction subgroups were seen; the majority of trials adopted a policy of induction at 41 completed weeks (287 days) or more.Fewer babies in the labour induction group had meconium aspiration syndrome (RR 0.50, 95% CI 0.34 to 0.73; eight trials, 2371 infants) compared with a policy of expectant management. There was no statistically significant difference between the rates of neonatal intensive care unit (NICU) admission for induction compared with expectant management (RR 0.90, 95% CI 0.78 to 1.04; 10 trials, 6161 infants). For women in the policy of induction arms of trials, there were significantly fewer caesarean sections compared with expectant management in 21 trials of 8749 women (RR 0.89, 95% CI 0.81 to 0.97).

AUTHORS' CONCLUSIONS

A policy of labour induction compared with expectant management is associated with fewer perinatal deaths and fewer caesarean sections. Some infant morbidities such as meconium aspiration syndrome were also reduced with a policy of post-term labour induction although no significant differences in the rate of NICU admission were seen.However, the absolute risk of perinatal death is small. Women should be appropriately counselled in order to make an informed choice between scheduled induction for a post-term pregnancy or monitoring without induction (or delayed induction).

Elective induction for pregnancies at or beyond 41 weeks of gestation and its impact on stillbirths: a systematic review with meta-analysis

Background

An important determinant of pregnancy outcome is the timely onset of labor and birth. Prolonged gestation complicates 5% to 10% of all pregnancies and confers increased risk to both the fetus and mother. The purpose of this review was to study the possible impact of induction of labour (IOL) for post-term pregnancies compared to expectant management on stillbirths.

Methods

A systematic review of the published studies including randomized controlled trials, quasi- randomized trials and observational studies was conducted. Search engines used were PubMed, the Cochrane Library, the WHO regional databases and hand search of bibliographies. A standardized data abstraction sheet was used. Recommendations have been made for input to the Lives Saved Tool (LiST) model by following standardized guidelines developed by the Child Health Epidemiology Reference Group (CHERG).

Results

A total of 25 studies were included in this review. Meta-analysis of 14 randomized controlled trials (RCTs) suggests that a policy of elective IOL for pregnancies at or beyond 41 weeks is associated with significantly fewer perinatal deaths (RR=0.31; 95% CI: 0.11-0.88) compared to expectant management, but no significant difference in the incidence of stillbirth (RR= 0.29; 95% CI: 0.06-1.38) was noted. The included trials evaluating this intervention were small, with few events in the intervention and control group. There was significant decrease in incidence of neonatal morbidity from meconium aspiration (RR = 0.43, 95% CI 0.23-0.79) and macrosomia (RR = 0.72; 95% CI: 0.54 – 0.98). Using CHERG rules, we recommended 69% reduction as a point estimate for the risk of stillbirth with IOL for prolonged gestation (> 41 weeks).

Conclusions

Induction of labour appears to be an effective way of reducing perinatal morbidity and mortality associated with post-term pregnancies. It should be offered to women with post-term pregnancies after discussing the benefits and risks of induction of labor.

Elective induction, selective deduction, and cesarean section

A recent systematic review found no "good quality evidence" that elective induction of labor confers substantial benefits to either mothers or babies, but concluded that elective induction is associated with a decreased risk of "cesarean delivery." Admittedly, elective induction was qualified as "at 41 weeks of gestation and beyond" with 42 weeks being proclaimed as the cutoff point between "elective" and "medically indicated." Major predictors of the success of any induction and the subsequent mode of delivery, such as parity and cervical status, were not taken into account. Crucial boundaries between what is elective and what is selective, what is medically indicated and what is not, and what is maternal request or persuasive coercion, remain as vague as ever.

Guidelines for the management of postterm pregnancy

A pregnancy reaching 42 completed weeks (294 days) is defined as postterm (PT). The use of ultrasound in early pregnancy for precise dating significantly reduces the number of PT pregnancies compared to dating based on the last menstrual period. Although the fetal, maternal and neonatal risks increase beyond 41 weeks, there is no conclusive evidence that prolongation of pregnancy, per se, is the major risk factor. Other specific risk factors for adverse outcomes have been identified, the most important of which are restricted fetal growth and fetal malformations. In order to prevent PT and associated complications routine induction before 42 weeks has been proposed. There is no conclusive evidence that this policy improves fetal, maternal and neonatal outcomes as compared to expectant management. It is also unclear if the rate of cesarean sections is different between the two management strategies. After careful identification and exclusion of specific risks, it would seem appropriate to let women make an informed decision about which management they wish to undertake. There is consensus that the number of inductions necessary to possibly avoid one stillbirth is very high. If induction is preferred, procedures for cervical ripening should be used, especially in nulliparous women. Close intrapartum fetal surveillance should be offered, irrespective of whether labor was induced or not.

Does routine induction of labour at 41 weeks really reduce the rate of caesarean section compared with expectant management?

OBJECTIVE

It is contended that routine induction of labour at 41 completed weeks of gestation reduces, or at least does not increase, a woman's chance of Caesarean section (CS), compared with expectant management. We wanted to know if this was true in our own hospital.

METHODS

We performed a retrospective review of 1367 nulliparous women who had reached 41+0 weeks undelivered with a live, singleton, fetus with a cephalic presentation. The women comprised two non-randomized contemporaneous cohorts: in one group, expectant management was planned, and in the second group the intention was to induce labour at 41 weeks. The primary outcome measure was the rate of CS in each group.

RESULTS

Of 645 women in whom expectant management was planned, 17.7% delivered by CS. Of 722 women in whom induction of labour was planned, 21.3% delivered by CS (P = 0.09). Of the total of 907 women in whom expectant management was planned or who laboured spontaneously before planned induction could be carried out, 16.6% delivered by CS. Of 460 women in whom induction was planned and actually carried out, 25.4% delivered by CS (P = 0.001).

CONCLUSION

The contention that routine induction of labour at 41 weeks reduces a woman's chance of delivery by Caesarean section was not supported by the findings of our study. Inducing labour may actually increase the nulliparous woman's risk of delivery by CS.

Postterm pregnancy: how can we improve outcomes?

Postterm pregnancy is defined as one which has progressed to 42 0/7 weeks or beyond. The most common reason to be diagnosed with a postterm pregnancy is inaccurate pregnancy dating, but it is also associated with obesity, nulliparity, and a prior history of postterm pregnancy. The rate of postterm pregnancy appears to be decreasing whether due to improved pregnancy dating or an increase in induction of labor. Postterm pregnancy is associated with both maternal and neonatal morbidity and fetal and neonatal mortality; similarly pregnancies beyond 41 weeks' gestation are associated with increases in these perinatal complications. Prevention of postterm pregnancies may include stripping or sweeping the membranes and unprotected coitus. Management of such pregnancies may include induction of labor and fetal antenatal monitoring. Individual patient management should involve careful counseling regarding the risks and benefits of each of the components of care.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the increasing risks of poor outcomes associated with prolonged pregnancy, demonstrate knowledge regarding gestational dating and use of cervical ripening agents in their care of pregnant women, and use evidence-based information when counseling their term patients regarding postterm pregnancy management.

Guidelines for the management of pregnancy at 41+0 to 42+0 weeks

OBJECTIVE

To provide evidence-based guidelines for the management of pregnancy at 41+0 to 42+0 weeks.

OUTCOMES

Reduction of perinatal mortality associated with Caesarean section at 41+0 to 42+0 weeks of pregnancy.

EVIDENCE

The Medline database, the Cochrane Library, and the American College of Obstetricians and Gynecologists and the Royal College of Obstetricians and Gynecologists, were searched for English language articles published between 1966 and March 2007, using the following key words: prolonged pregnancy, post-term pregnancy, and postdates pregnancy. The quality of evidence was evaluated and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care. Recommendations 1. First trimester ultrasound should be offered, ideally between 11 and 14 weeks, to all women, as it is a more accurate assessment of gestational age than last menstrual period with fewer pregnancies prolonged past 41+0 weeks. (I-A) 2. If there is a difference of greater than 5 days between gestational age dated using the last menstrual period and first trimester ultrasound, the estimated date of delivery should be adjusted as per the first trimester ultrasound. (I-A) 3. If there is a difference of greater than 10 days between gestational age dated using the last menstrual period and second trimester ultrasound, the estimated date of delivery should be adjusted as per the second trimester ultrasound. (I-A) 4. When there has been both a first and second trimester ultrasound, gestational age should be determined by the earliest ultrasound. (I-A) 5. Women should be offered the option of membrane sweeping commencing at 38 to 41 weeks, following a discussion of risks and benefits. (I-A) 6. Women should be offered induction at 41+0 to 42+0 weeks, as the present evidence reveals a decrease in perinatal mortality without increased risk of Caesarean section. (I-A) 7. Antenatal testing used in the monitoring of the 41- to 42-week pregnancy should include at least a non-stress test and an assessment of amniotic fluid volume. (I-A) 8. Each obstetrical department should establish guidelines dependent on local resources for scheduling of labour induction. (I-A).

Variation in rates of postterm birth in Europe: reality or artefact?

OBJECTIVE

To compare rates of postterm birth in Europe.

DESIGN

Analysis of data from vital statistics, birth registers, and national birth samples collected for the PERISTAT project.

SETTING

Thirteen European countries.

POPULATION

All live births or representative samples of births for the year 2000 or most recent year available.

METHODS

Comparison of national and regional rates of postterm birth. Other indicators (birthweight, deliveries with a non-spontaneous onset and mortality) were used to assess the validity of postterm rates.

MAIN OUTCOME MEASURES

The proportion of births at 42 completed weeks of gestation or later.

RESULTS

Postterm rates varied greatly, from 0.4% (Austria, Belgium) to over 7% (Denmark, Sweden) of births. Higher postterm rates were associated with a greater proportion of babies with birthweight 4500 g or more. Fetal and early neonatal mortality rates were higher among postterm births than among births at 40 weeks. Countries with higher proportions of births with a nonspontaneous onset of labour had lower postterm birth rates. The shapes of the gestational-age distributions at term varied. In some countries, there was a sharp cutoff in deliveries at 40 weeks, while elsewhere this occurred at 41 weeks.

CONCLUSIONS

These results suggest that practices for managing pregnancies continuing beyond term differ in Europe and raise questions about the health and other impacts in countries with markedly high or low postterm rates. Some variability in these rates may also be due to methods for determining gestational age, which has broader implications for international comparisons of gestational age, including rates of postterm and preterm births and small-for-gestational-age newborns.

Prolonged Pregnancy:

The timely onset of labor and birth is an important determinant of perinatal outcome. Prolonged (postterm) pregnancy--defined as delivery at or beyond 42 weeks' gestation--complicates 10% of all gestations and is associated with increased risks to both fetus (stillbirth, macrosomia, birth injury, meconium aspiration syndrome) and mother (cesarean delivery, severe perineal injury, postpartum hemorrhage). The risk of routine induction of labor (failed induction leading to cesarean delivery) in the era of cervical ripening is lower than previously reported. For these reasons, the authors favor a policy of routine induction of labor for low-risk pregnancies at 41 weeks' gestation.

Influence of parity on fetal mortality in prolonged pregnancy

OBJECTIVE

In England an estimated 50,000 inductions of labour at or beyond 41 weeks' gestation are conducted each year. However, the published evidence on the effect of parity on stillbirth in prolonged pregnancy is limited, and has produced conflicting data. The aim of this study is to evaluate the influence of parity on fetal mortality in prolonged pregnancies.

STUDY DESIGN

Retrospective analysis of 145,695 singleton births with known parity and no malformation noted at birth to residents in the former North-East Thames Region, UK. The parity and gestation specific stillbirth risks and relative risks per 1000 ongoing pregnancies were calculated in relation to parity between 37 and 45 weeks.

RESULTS

Before 41 weeks the stillbirth risk rose gradually but did not differ by parity. By 41 weeks there was a substantial increase in the stillbirth risk in nulliparous women but not in parous women. The pattern of rise is such that the stillbirth risk is 2.9 times higher (95% CI 1.06-8.19) in nulliparous women at >42 weeks' gestation.

CONCLUSION

Being parous appears to have a protective effect on fetal mortality in prolonged pregnancy. These findings question the need for routine induction of labour at 41 weeks in parous women.

Induction of labour for improving birth outcomes for women at or beyond term

BACKGROUND

As a pregnancy continues beyond term the risks of babies dying inside the womb or in the immediate newborn period increase. Whether a policy of labour induction at a predetermined gestational age can reduce this increased risk is the subject of this review.

OBJECTIVES

To evaluate the benefits and harms of a policy of labour induction at term or post-term compared to awaiting spontaneous labour or later induction of labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2006).

SELECTION CRITERIA

Randomized controlled trials conducted in women at or beyond term. The eligible trials were those comparing a policy of labour induction to a policy of awaiting spontaneous onset of labour. Trials comparing cervical ripening methods, membrane stripping/sweeping or nipple stimulation without any commitment to delivery within a certain time were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated potentially eligible trials and extracted data. Outcomes are analysed in two main categories: gestational age and cervix status.

MAIN RESULTS

We included 19 trials reporting on 7984 women. A policy of labour induction at 41 completed weeks or beyond was associated with fewer (all-cause) perinatal deaths (1/2986 versus 9/2953; relative risk (RR) 0.30; 95% confidence interval (CI) 0.09 to 0.99). The risk difference is 0.00 (95% CI 0.01 to 0.00). If deaths due to congenital abnormality are excluded, no deaths remain in the labour induction group and seven deaths remain in the no-induction group. There was no evidence of a statistically significant difference in the risk of caesarean section (RR 0.92; 95% CI 0.76 to 1.12; RR 0.97; 95% CI 0.72 to 1.31) for women induced at 41 and 42 completed weeks respectively. Women induced at 37 to 40 completed weeks were more likely to have a caesarean section with expectant management than those in the labour induction group (RR 0.58; 95% CI 0.34 to 0.99). There were fewer babies with meconium aspiration syndrome (41+: RR 0.29; 95% CI 0.12 to 0.68, four trials, 1325 women; 42+: RR 0.66; 95% CI 0.24 to 1.81, two trials, 388 women).

AUTHORS' CONCLUSIONS

A policy of labour induction after 41 completed weeks or later compared to awaiting spontaneous labour either indefinitely or at least one week is associated with fewer perinatal deaths. However, the absolute risk is extremely small. Women should be appropriately counselled on both the relative and absolute risks.

When to induce labor for post-term? A study of induction at 41 weeks versus 42 weeks

OBJECTIVE

To evaluate the pregnancy outcomes of two policies of timing of induction of labor for post-term pregnancies.

STUDY DESIGN

It is a retrospective study in a University obstetric unit from 1997 to 2002. Five thousand eight hundred and ninety-two singleton, cephalic pregnancies with gestational age at delivery at or more than 41 completed weeks were studied. They were divided into two groups. Group A included women who delivered from January 1997 to February 1999 when the policy of the department was to induce labor for post-maturity at 42 weeks of gestation. Group B included those delivered between March 1999 and December 2002 when the timing of induction for post-term was advanced to 41 weeks. The intrapartum characteristics, delivery and perinatal outcomes were analyzed by Student's t-test and Chi-square test for continuous and categorical variables, respectively.

RESULTS

Two thousand one hundred and seventy-six women were studied in Group A and 3716 in Group B. Twenty-nine percent of these pregnancies in Group A required induction of labor whereas 20.3% were for post-term. In Group B, 58% of pregnancies had labor induction and 55% for post-maturity. For the pregnancies undergoing induction of labor for post-term, both the duration of labor (P<0.001) and the need of intrapartum epidural analgesia were increased (OR 1.3, 95% CI: 1.0-1.6) in Group B. However, there was no significant difference in the mode of delivery, apgar scores and stillbirths between the two study periods.

CONCLUSION

Compared to routine induction at 42 weeks, induction at 41 weeks is associated with a significantly higher risk of use of medical interventions and associated complications, with no observable benefits.

The use of fetal Doppler cerebroplacental blood flow and amniotic fluid volume measurement in the surveillance of postdated pregnancies

BACKGROUND

This prospective observational study aims at determining the distribution of fetal cerebro-placental Doppler indices and amniotic fluid volume in a homogenous group of uncomplicated postdated pregnancies at 41 weeks. The correlation with incidence of passage of thick meconium-stained liquor in labor was analyzed to decide which parameter would be useful in the surveillance of postdated pregnancies.

METHODS

The amniotic fluid volume, middle cerebral artery pulsatility index, umbilical artery pulsatility index, and cerebroplacental ratio were measured and distribution determined in 118 well-dated singleton pregnancies admitted for routine induction of labor at 41 weeks. The 10th centile and the 90th centile in each Doppler parameter and amniotic fluid volume were chosen to divide each parameter into three centile groups. The prevalence of thick meconium-stained liquor in labor in different Doppler and amniotic fluid volume centile groups was compared using Chi-square test for trend with P < 0.05 taken as statistically significant.

RESULTS

The prevalence of thick meconium-stained liquor in labor was significantly inversely correlated with the middle cerebral artery pulsatility index (P = 0.008), with significant difference across different middle cerebral artery pulsatility index centile groups (P = 0.02). There was no significant difference in the prevalence of thick meconium-stained liquor in labor or oligohydramnios across different umbilical artery pulsatility index centile groups. Neither was there significant difference in the prevalence of thick meconium-stained liquor in labor and oligohydramnios across different cerebroplacental ratio and amniotic fluid volume centile groups. Logistic regression using the 10th centile of middle cerebral artery pulsatility index confirmed that it was a significant independent predicting factor for risk of thick meconium-stained liquor in labor with adjusted odds ratio (95th CI) of 6.14 (1.6-24.1).

CONCLUSION

Middle cerebral artery pulsatility index is better than amniotic fluid volume or umbilical artery pulsatility index in predicting the risk of thick meconium-stained liquor in labor in uncomplicated postdated pregnancy at 41 weeks.

Induction of labor with three different techniques at 41 weeks of gestation or spontaneous follow-up until 42 weeks in women with definitely unfavorable cervical scores

OBJECTIVE

To compare the obstetric outcome of induction of labor at 41 weeks and of follow-up until 42 weeks and induction if the patient has still not given birth at 42 weeks.

STUDY DESIGN

Six hundred women at 287+/-1 days of gestation with definitely unfavorable cervical scores were randomized to labor induction (N=300) or spontaneous follow-up (N=300) with twice-weekly nonstress testing and amniotic fluid measurement and once-weekly biophysical scoring. The treatments used in the induction group were (1) vaginal administration of 50 microg misoprostol (n=100), (2) oxytocin induction (n=100), and (3) transcervical insertion of a Foley balloon (n=100). The primary outcome measures were the cesarean delivery rate, whether or not the normal hospital stay had to be extended, and the neonatal outcomes. Secondary outcome measure included number of emergency cesarean deliveries performed for abnormalities of the fetal heart rate (FHR).

RESULTS

The abdominal delivery rate was 19.3% in the induction group and 22% in the follow-up group (p=0.4). The mean length of hospital stay in the two main groups was 1.4+/-0.8 days and 1.3+/-1 days, respectively (p=0.1). Significantly higher rates of macrosomia and shoulder dystocia were seen in the follow-up group (24.6 and 2.3%) than in the induction group (7.6%, p<0.001; 0.3%, p=0.03). Meconium-stained amniotic fluid and meconium aspiration syndrome were observed significantly less frequently in the induction group (9.3 and 1.3%) than in the follow-up group (20.3%, p<0.001; 4%, p=0.03). Rates of emergency abdominal delivery in response to worrying FHR traces, neonatal intensive care unit admission, and low umblical artery pH were similar in the two groups. There was one intrauterine fetal death in the follow-up group.

CONCLUSION

Induction of labor at 41 weeks of gestation does not increase the cesarean delivery rate or cause a longer stay in hospital than follow-up until 42 weeks, and neonatal morbidity is also lower after induction.

Reference ranges for umbilical and middle cerebral artery pulsatility index and cerebroplacental ratio in prolonged pregnancies

OBJECTIVE

To construct normal ranges for umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI) and cerebroplacental ratio (CPR) in prolonged pregnancies according to strict methodological criteria using polynomial regression analysis.

METHODS

This was a retrospective, cross-sectional observational study involving 140 women, 10 women for each gestational day between 287 and 300 days of gestation. Fetal Doppler parameters were assessed to construct normal reference ranges for UA PI and MCA PI. CPR was calculated as a ratio of MCA PI/UA PI.

RESULTS

Mathematical modeling of the data demonstrated that the optimal fit was a linear polynomial one. Mean, 5th and 95th centiles were calculated for UA, MCA and CPR and centile curves from the regression analysis were constructed.

CONCLUSIONS

Reference ranges for UA PI, MCA PI and CPR in prolonged pregnancies have been constructed. MCA PI shows a wider range than previously reported in the literature.

The rhetoric of “natural” in natural childbirth: childbearing women's perspectives on prolonged pregnancy and induction of labour

It is widely known that the notion of prolonged pregnancy, defined medically as 41+ or 42+ weeks gestation, has been hotly debated within the medical and midwifery communities for many decades. Within this debate, pregnant women's voices have rarely been heard. Presented here are the results of a qualitative study of self-care in pregnancy, birth and lactation with a non-random sample of women in British Columbia, Canada. A panel of 27 women was interviewed in the third trimester of pregnancy, and 23 of the same participants were re-interviewed post-partum (50 interviews in total). Interviews were tape-recorded, transcribed, and analyzed thematically. Many of the women said they favoured a natural birth and were opposed to labour induction at the time of the first interview. Yet all but one of the ten women who went beyond 40 weeks gestation used self-help measures to stimulate labour. These women did not perceive prolonged pregnancy as a medical problem per se. Rather they saw it as an inconvenience, a worry to their friends, families and maternity care providers, and a prolongation of physical discomfort. The findings are interpreted by examining the literature on the medicalization/healthicization of childbirth.