Management of prolonged pregnancy: results of a prospective randomized trial

Meconium-stained amniotic fluid

Green-stained amniotic fluid, often referred to as meconium-stained amniotic fluid, is present in 5% to 20% of patients in labor and is considered an obstetric hazard. The condition has been attributed to the passage of fetal colonic content (meconium), intraamniotic bleeding with the presence of heme catabolic products, or both. The frequency of green-stained amniotic fluid increases as a function of gestational age, reaching approximately 27% in post-term gestation. Green-stained amniotic fluid during labor has been associated with fetal acidemia (umbilical artery pH <7.00), neonatal respiratory distress, and seizures as well as cerebral palsy. Hypoxia is widely considered a mechanism responsible for fetal defecation and meconium-stained amniotic fluid; however, most fetuses with meconium-stained amniotic fluid do not have fetal acidemia. Intraamniotic infection/inflammation has emerged as an important factor in meconium-stained amniotic fluid in term and preterm gestations, as patients with these conditions have a higher rate of clinical chorioamnionitis and neonatal sepsis. The precise mechanisms linking intraamniotic inflammation to green-stained amniotic fluid have not been determined, but the effects of oxidative stress in heme catabolism have been implicated. Two randomized clinical trials suggest that antibiotic administration decreases the rate of clinical chorioamnionitis in patients with meconium-stained amniotic fluid. A serious complication of meconium-stained amniotic fluid is meconium aspiration syndrome. This condition develops in 5% of cases presenting with meconium-stained amniotic fluid and is a severe complication typical of term newborns. Meconium aspiration syndrome is attributed to the mechanical and chemical effects of aspirated meconium coupled with local and systemic fetal inflammation. Routine naso/oropharyngeal suctioning and tracheal intubation in cases of meconium-stained amniotic fluid have not been shown to be beneficial and are no longer recommended in obstetrical practice. A systematic review of randomized controlled trials suggested that amnioinfusion may decrease the rate of meconium aspiration syndrome. Histologic examination of the fetal membranes for meconium has been invoked in medical legal litigation to time the occurrence of fetal injury. However, inferences have been largely based on the results of in vitro experiments, and extrapolation of such findings to the clinical setting warrants caution. Fetal defecation throughout gestation appears to be a physiologic phenomenon based on ultrasound as well as in observations in animals.

Induction of labour at or beyond 37 weeks' gestation

BACKGROUND

Risks of stillbirth or neonatal death increase as gestation continues beyond term (around 40 weeks' gestation). It is unclear whether a policy of labour induction can reduce these risks. This Cochrane Review is an update of a review that was originally published in 2006 and subsequently updated in 2012 and 2018.

OBJECTIVES

To assess the effects of a policy of labour induction at or beyond 37 weeks' gestation compared with a policy of awaiting spontaneous labour indefinitely (or until a later gestational age, or until a maternal or fetal indication for induction of labour arises) on pregnancy outcomes for the infant and the mother.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (17 July 2019), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) conducted in pregnant women at or beyond 37 weeks, comparing a policy of labour induction with a policy of awaiting spontaneous onset of labour (expectant management). We also included trials published in abstract form only. Cluster-RCTs, quasi-RCTs and trials using a cross-over design were not eligible for inclusion in this review. We included pregnant women at or beyond 37 weeks' gestation. Since risk factors at this stage of pregnancy would normally require intervention, only trials including women at low risk for complications, as defined by trialists, were eligible. The trials of induction of labour in women with prelabour rupture of membranes at or beyond term were not considered in this review but are considered in a separate Cochrane Review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, assessed risk of bias and extracted data. Data were checked for accuracy. We assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

In this updated review, we included 34 RCTs (reporting on over 21,000 women and infants) mostly conducted in high-income settings. The trials compared a policy to induce labour usually after 41 completed weeks of gestation (> 287 days) with waiting for labour to start and/or waiting for a period before inducing labour. The trials were generally at low to 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) 0.15 to 0.64; 22 trials, 18,795 infants; high-certainty evidence). There were four perinatal deaths in the labour induction policy group compared with 25 perinatal deaths in the expectant management group. The number needed to treat for an additional beneficial outcome (NNTB) with induction of labour, in order to prevent one perinatal death, was 544 (95% CI 441 to 1042). There were also fewer stillbirths in the induction group (RR 0.30, 95% CI 0.12 to 0.75; 22 trials, 18,795 infants; high-certainty evidence); two in the induction policy group and 16 in the expectant management group. For women in the policy of induction arms of trials, there were probably fewer caesarean sections compared with expectant management (RR 0.90, 95% CI 0.85 to 0.95; 31 trials, 21,030 women; moderate-certainty evidence); and probably little or no difference in operative vaginal births with induction (RR 1.03, 95% CI 0.96 to 1.10; 22 trials, 18,584 women; moderate-certainty evidence). Induction may make little or difference to perineal trauma (severe perineal tear: RR 1.04, 95% CI 0.85 to 1.26; 5 trials; 11,589 women; low-certainty evidence). Induction probably makes little or no difference to postpartum haemorrhage (RR 1.02, 95% CI 0.91 to 1.15, 9 trials; 12,609 women; moderate-certainty evidence), or breastfeeding at discharge (RR 1.00, 95% CI 0.96 to 1.04; 2 trials, 7487 women; moderate-certainty evidence). Very low certainty evidence means that we are uncertain about the effect of induction or expectant management on the length of maternal hospital stay (average mean difference (MD) -0.19 days, 95% CI -0.56 to 0.18; 7 trials; 4120 women; Tau² = 0.20; I² = 94%). Rates of neonatal intensive care unit (NICU) admission were lower (RR 0.88, 95% CI 0.80 to 0.96; 17 trials, 17,826 infants; high-certainty evidence), and probably fewer babies had Apgar scores less than seven at five minutes in the induction groups compared with expectant management (RR 0.73, 95% CI 0.56 to 0.96; 20 trials, 18,345 infants; moderate-certainty evidence). Induction or expectant management may make little or no difference for neonatal encephalopathy (RR 0.69, 95% CI 0.37 to 1.31; 2 trials, 8851 infants; low-certainty evidence, and probably makes little or no difference for neonatal trauma (RR 0.97, 95% CI 0.63 to 1.49; 5 trials, 13,106 infants; moderate-certainty evidence) for induction compared with expectant management. Neurodevelopment at childhood follow-up and postnatal depression were not reported by any trials. In subgroup analyses, no differences were seen for timing of induction (< 40 versus 40-41 versus > 41 weeks' gestation), by parity (primiparous versus multiparous) or state of cervix for any of the main outcomes (perinatal death, stillbirth, NICU admission, caesarean section, operative vaginal birth, or perineal trauma).

AUTHORS' CONCLUSIONS

There is a clear reduction in perinatal death with a policy of labour induction at or beyond 37 weeks compared with expectant management, though absolute rates are small (0.4 versus 3 deaths per 1000). There were also lower caesarean rates without increasing rates of operative vaginal births and there were fewer NICU admissions with a policy of induction. Most of the important outcomes assessed using GRADE had high- or moderate-certainty ratings. While existing trials have not yet reported on childhood neurodevelopment, this is an important area for future research. The optimal timing of offering induction of labour to women at or beyond 37 weeks' gestation needs further investigation, as does further exploration of risk profiles of women and their values and preferences. Offering women tailored counselling may help them make an informed choice between induction of labour for pregnancies, particularly those continuing beyond 41 weeks - or waiting for labour to start and/or waiting before inducing labour.

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

BACKGROUND

Beyond term, the risks of stillbirth or neonatal death increase. It is unclear whether a policy of labour induction can reduce these risks. This Cochrane review is an update of a review that was originally published in 2006 and subsequently updated in 2012 OBJECTIVES: To assess the effects of a policy of labour induction at or beyond term compared with a policy of awaiting spontaneous labour or until an indication for birth induction of labour is identified) on pregnancy outcomes for infant and mother.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (9 October 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) conducted in pregnant women at or beyond term, comparing a policy of labour induction with a policy of awaiting spontaneous onset of labour (expectant management). We also included trials published in abstract form only. Cluster-RCTs, quasi-RCTs and trials using a cross-over design are not eligible for inclusion in this review.We included pregnant women at or beyond term. Since a risk factor at this stage of pregnancy would normally require an intervention, only trials including women at low risk for complications were eligible. We accepted the trialists' definition of 'low risk'. The trials of induction of labour in women with prelabour rupture of membranes at or beyond term were not considered in this review but are considered in a separate Cochrane review.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for inclusion, assessed risk of bias and extracted data. Data were checked for accuracy. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

In this updated review, we included 30 RCTs (reporting on 12,479 women). The trials took place in Norway, China, Thailand, the USA, Austria, Turkey, Canada, UK, India, Tunisia, Finland, Spain, Sweden and the Netherlands. They were generally at a 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) 0.33, 95% confidence interval (CI) 0.14 to 0.78; 20 trials, 9960 infants; moderate-quality evidence). There were two perinatal deaths in the labour induction policy group compared with 16 perinatal deaths in the expectant management group. The number needed to treat to for an additional beneficial outcome (NNTB) with induction of labour in order to prevent one perinatal death was 426 (95% CI 338 to 1337). There were fewer stillbirths in the induction group (RR 0.33, 95% CI 0.11 to 0.96; 20 trials, 9960 infants; moderate-quality evidence); there was one stillbirth in the induction policy arm and 10 in the expectant management group.For women in the policy of induction arms of trials, there were fewer caesarean sections compared with expectant management (RR 0.92, 95% CI 0.85 to 0.99; 27 trials, 11,738 women; moderate-quality evidence); and a corresponding marginal increase in operative vaginal births with induction (RR 1.07, 95% CI 0.99 to 1.16; 18 trials, 9281 women; moderate-quality evidence). There was no evidence of a difference between groups for perineal trauma (RR 1.09, 95% CI 0.65 to 1.83; 4 trials; 3028 women; low-quality evidence), postpartum haemorrhage (RR 1.09 95% CI 0.92 to 1.30, 5 trials; 3315 women; low-quality evidence), or length of maternal hospital stay (average mean difference (MD) -0.34 days, 95% CI -1.00 to 0.33; 5 trials; 1146 women; Tau² = 0.49; I² 95%; very low-quality evidence).Rates of neonatal intensive care unit (NICU) admission were lower (RR 0.88, 95% CI 0.77 to 1.01; 13 trials, 8531 infants; moderate-quality evidence) and fewer babies had Apgar scores less than seven at five minutes in the induction groups compared with expectant management (RR 0.70, 95% CI 0.50 to 0.98; 16 trials, 9047 infants; moderate-quality evidence).There was no evidence of a difference for neonatal trauma (RR 1.18, 95% CI 0.68 to 2.05; 3 trials, 4255 infants; low-quality evidence), for induction compared with expectant management.Neonatal encephalopathy, neurodevelopment at childhood follow-up, breastfeeding at discharge and postnatal depression were not reported by any trials.In subgroup analyses, no clear differences between timing of induction (< 41 weeks versus ≥ 41 weeks' gestation) or by state of cervix were seen for perinatal death, stillbirth, NICU admission, caesarean section, or perineal trauma. However, operative vaginal birth was more common in the inductions at < 41 weeks' gestation subgroup compared with inductions at later gestational ages. The majority of trials (about 75% of participants) adopted a policy of induction at ≥ 41 weeks (> 287 days) gestation for the intervention arm.

AUTHORS' CONCLUSIONS

A policy of labour induction at or beyond term compared with expectant management is associated with fewer perinatal deaths and fewer caesarean sections; but more operative vaginal births. NICU admissions were lower and fewer babies had low Apgar scores with induction. No important differences were seen for most of the other maternal and infant outcomes.Most of the important outcomes assessed using GRADE had a rating of moderate or low-quality evidence - with downgrading decisions generally due to study limitations such as lack of blinding (a condition inherent in comparisons between a policy of acting and of waiting), or imprecise effect estimates. One outcome (length of maternal stay) was downgraded further to very low-quality evidence due to inconsistency.Although the absolute risk of perinatal death is small, it may be helpful to offer women appropriate counselling to help choose between scheduled induction for a post-term pregnancy or monitoring without (or later) induction).The optimal timing of offering induction of labour to women at or beyond term warrants further investigation, as does further exploration of risk profiles of women and their values and preferences. Individual participant meta-analysis is likely to help elucidate the role of factors, such as parity, in influencing outcomes of induction compared with expectant management.

Onset of Labor in Post-Term Pregnancy by Chamomile

Background

Post-term pregnancy is an important factor in perinatal mortality and morbidity. Generally, to reduce perinatal mortality in pregnancy, the delivery is done before adverse perinatal morbidity occurs. To prevent prolonged pregnancy, labor is induced with chemical drugs and complementary therapies. Due to the side effects and contraindications of chemical medicine, the use of herbs has been investigated in the induction of labor in post-term pregnancy.

Objectives

This study was done to identify the effect of chamomile on inducing labor in women with post-term pregnancy of Shahid Akbarabadi hospital in Tehran in 2013.

Patients and Methods

This double-blind clinical trial study was performed in Iran on 80 post-term pregnant women with a gestational age of 40 weeks or more, a single pregnancy, 18 - 35 years old, cephalic presentation, an estimated fetal weight of 2500 - 4000 grams, an absence of uterine contraction, a cervical Bishop score of less than 4, the safety of the membrane, and low-risk pregnancy; they were randomly assigned to one of two groups of 40 women. Each of the participants was given a bottle containing 42 capsules (500 mg each) and took 2 capsules every 8 hours. The data were collected through the questionnaire of demographic observational, and examinal characteristics. Descriptive statistics, independent samples t-test, and Fisher’s exact test using SPSS (16/win) were used to determine and compare the effects of drugs on inducing labor in the groups.

Results

After a week of using the first dose, the results showed that in 92.5% of the chamomile group and 62.5% in the placebo group, delivery symptoms started after taking the oral capsules, and there were significant statistical differences between the two groups for the onset of labor (P = 0.003) There was a noticeable statistical difference between the two groups regarding the mean interval time to the onset of labor pain after taking the capsules (P = 0.000).

Conclusions

In this study¸ chamomile stimulated labor in post-term pregnancy. With further studies, chamomile, which has no chemical side effects, can be suggested for stimulating labor in post-term pregnancy.

Bacteria and endotoxin in meconium-stained amniotic fluid at term: could intra-amniotic infection cause meconium passage?

BACKGROUND

Meconium-stained amniotic fluid (MSAF) is a common occurrence among women in spontaneous labor at term, and has been associated with adverse outcomes in both mother and neonate. MSAF is a risk factor for microbial invasion of the amniotic cavity (MIAC) and preterm birth among women with preterm labor and intact membranes. We now report the frequency of MIAC and the presence of bacterial endotoxin in the amniotic fluid of patients with MSAF at term.

MATERIALS AND METHODS

We conducted a cross-sectional study including women in presumed preterm labor because of uncertain dates who underwent amniocentesis, and were later determined to be at term (n = 108). Patients were allocated into two groups: (1) MSAF (n = 66) and (2) clear amniotic fluid (n = 42). The presence of bacteria was determined by microbiologic techniques, and endotoxin was detected using the Limulus amebocyte lysate (LAL) gel clot assay. Statistical analyses were performed to test for normality and bivariate comparisons.

RESULTS

Bacteria were more frequently present in patients with MSAF compared to those with clear amniotic fluid [19.6% (13/66) versus 4.7% (2/42); p < 0.05]. The microorganisms were Gram-negative rods (n = 7), Ureaplasma urealyticum (n = 4), Gram-positive rods (n = 2) and Mycoplasma hominis (n = 1). The LAL gel clot assay was positive in 46.9% (31/66) of patients with MSAF, and in 4.7% (2/42) of those with clear amniotic fluid (p < 0.001). After heat treatment, the frequency of a positive LAL gel clot assay remained higher in the MSAF group [18.1% (12/66) versus 2.3% (1/42), p < 0.05]. Median amniotic fluid IL-6 concentration (ng/mL) was higher [1.3 (0.7-1.9) versus 0.6 (0.3-1.2), p = 0.04], and median amniotic fluid glucose concentration (mg/dL) was lower [6 (0-8.9) versus 9 (7.4-12.6), p < 0.001] in the MSAF group, than in those with clear amniotic fluid.

CONCLUSION

MSAF at term was associated with an increased incidence of MIAC. The index of suspicion for an infection-related process in postpartum women and their neonates should be increased in the presence of MSAF.

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).

Intravenous oxytocin alone for cervical ripening and induction of labour

BACKGROUND

Oxytocin is the commonest induction agent used worldwide. It has been used alone, in combination with amniotomy or following cervical ripening with other pharmacological or non-pharmacological methods.

OBJECTIVES

To determine the effects of oxytocin alone for third trimester cervical ripening and induction of labour in comparison with other methods of induction of labour or placebo/no treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2009) and bibliographies of relevant papers.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing intravenous oxytocin with placebo or no treatment, or with prostaglandins (vaginal or intracervical) for third trimester cervical ripening or labour induction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and carried out data extraction.

MAIN RESULTS

Sixty-one trials (12,819 women) are included.When oxytocin inductions were compared with expectant management, fewer women failed to deliver vaginally within 24 hours (8.4% versus 53.8%, risk ratio (RR) 0.16, 95% confidence interval (CI) 0.10 to 0.25). There was a significant increase in the number of women requiring epidural analgesia (RR 1.10, 95% CI 1.04 to 1.17). Fewer women were dissatisfied with oxytocin induction in the one trial reporting this outcome (5.9% versus 13.7%, RR 0.43, 95% CI 0.33 to 0.56).Compared with vaginal prostaglandins, oxytocin increased unsuccessful vaginal delivery within 24 hours in the two trials reporting this outcome (70% versus 21%, RR 3.33, 95% CI 1.61 to 6.89). There was a small increase in epidurals when oxytocin alone was used (RR 1.09, 95% CI 1.01 to 1.17).Most of the studies included women with ruptured membranes, and there was some evidence that vaginal prostaglandin increased infection in mothers (chorioamnionitis RR 0.66, 95% CI 0.47 to 0.92) and babies (use of antibiotics RR 0.68, 95% CI 0.53 to 0.87). These data should be interpreted cautiously as infection was not pre-specified in the original review protocol.When oxytocin was compared with intracervical prostaglandins, there was an increase in unsuccessful vaginal delivery within 24 hours (50.4% versus 34.6%, RR 1.47, 95% CI 1.10 to 1.96) and an increase in caesarean sections (19.1% versus 13.7%, RR 1.37, 95% CI 1.08 to 1.74) in the oxytocin group.

AUTHORS' CONCLUSIONS

Comparison of oxytocin with either intravaginal or intracervical PGE2 reveals that the prostaglandin agents probably increase the chances of achieving vaginal birth within 24 hours. Oxytocin induction may increase the rate of interventions in labour.A suggestion that for women with prelabour rupture of membranes induction with vaginal prostaglandin may increase risk of infection for mother and baby warrants further study.

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.

Postterm pregnancy: should all women have labour induced? A review of the literature

All pregnancies are at some risk of adverse fetal and neonatal outcome. The risk increases, however, if the pregnancy ends too soon (preterm), or if it ends too late (postterm).

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.

Prolonged pregnancy: the management dilemma

In a prospective randomized study, pregnancies with unfavorable cervix and well established gestational age of at least 42 weeks were selected for management by either antepartum fetal testing or prostaglandin gel induction of labor. Of the 108 pregnancies studied, 57 (53%) had labor induced and 51 (47%) continued without intervention. Comparison of the two groups showed no difference in meconium staining, fetal distress, length of first stage of labor, the need for intervention, or the mode of delivery. In terms of Apgar score the neonatal outcome was not significantly different but a greater proportion of the babies (7.8% versus 1.8%) in the noninduced group required intubation. Our data show that there is no particular advantage in letting the pregnancy go beyond 42 completed weeks of gestation especially if prostaglandin is available for induction of labor.

Intravenous oxytocin alone for cervical ripening and induction of labour

BACKGROUND

Oxytocin is the commonest induction agent used worldwide. It has been used alone, in combination with amniotomy or following cervical ripening with other pharmacological or non-pharmacological methods. Prior to the introduction of prostaglandin agents oxytocin was used as a cervical ripening agent as well. In developed countries oxytocin alone is more commonly used in the presence of ruptured membranes whether spontaneous or artificial. In developing countries where the incidence of HIV is high, delaying amniotomy in labour reduces vertical transmission rates and hence the use of oxytocin with intact membranes warrants further investigation. This review will address the use of oxytocin alone for induction of labour. Amniotomy alone or oxytocin with amniotomy for induction of labour has been reviewed elsewhere in the Cochrane Library. Trials which consider concomitant administration of oxytocin and amniotomy will not be considered. This is one of a series of reviews of methods of cervical ripening and labour induction using a standardised methodology.

OBJECTIVES

To determine the effects of oxytocin alone for third trimester cervical ripening or induction of labour in comparison with other methods of induction of labour or placebo/no treatment.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Trials Register, the Cochrane Controlled Trials Register and bibliographies of relevant papers. Last searched: May 2001.

SELECTION CRITERIA

The criteria for inclusion included the following: (1) clinical trials comparing vaginal 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; (2) random allocation to the treatment or control group; (3) adequate allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.

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. The initial data extraction was done centrally, and incorporated into a series of primary reviews arranged by methods of induction of labour, following a standardised methodology. The data is to be extracted from the primary reviews into a series of secondary reviews, arranged by category of woman.

MAIN RESULTS

In total, 110 trials were considered; 52 have been excluded and 58 included examining a total of 11,129 women. Comparing oxytocin alone with expectant management: Oxytocin alone reduced the rate of unsuccessful vaginal delivery within 24 hours when compared with expectant management (8.3% versus 54%, relative risk (RR) 0.16, 95% confidence interval (CI) 0.10,0.25) but the caesarean section rate was increased (10.4% versus 8.9%, RR 1.17, 95% CI 1.01,1.36). This increase in caesarean section rate was not apparent in the subgroup analyses. Women were less likely to be unsatisfied with induction rather than expectant management, in the one trial reporting this outcome (5.5% versus 13.7%, RR 0.43, 95% CI 0.33, 0.56). Comparing oxytocin alone with vaginal prostaglandins: Oxytocin alone was associated with an increase in unsuccessful vaginal delivery within 24 hours (52% versus 28%, RR 1.85, 95% CI 1.41, 2.43), irrespective of membrane status, but there was no difference in caesarean section rates (11.4% versus 10%, RR 1.12, 95% CI 0.95, 1.33). Comparing oxytocin alone with intracervical prostaglandins: Oxytocin alone was associated with an increase in unsuccessful vaginal delivery within 24 hours when compared with intracervical PGE2 (51% versus 35%, RR 1.49, 95% CI 1.12,1.99). For all women with an unfavourable cervix regardless of membrane status, the caesarean section rates were increased (19.0% versus 13.1%, RR 1.42, 95% CI 1.11, 1.82).

REVIEWER'S CONCLUSIONS

Overall, comparison of oxytocin alone with either intravaginal or intracervical PGE2 reveals that the prostaglandin agents probably overall have more benefits than oxytocin alone. The amount of information relating to specific clinical subgroups is limited, especially with respect to women with intact membranes. Comparison of oxytocin alone to vaginal PGE2 in women with ruptured membranes reveals that both interventions are probably equally efficacious with each having some advantages and disadvantages over the others. With respect to current practice in women with ruptured membranes induction can be recommended by either method and in women with intact membranes there is insufficient information to make firm recommendations.

Obstetric outcome in uncomplicated prolonged pregnancy

OBJECTIVE

To study and compare the obstetric outcome in term pregnancies and uncomplicated prolonged pregnancies.

METHODS

The study was a retrospective review of 596 cases. The case notes of 286 patients with uncomplicated prolonged pregnancies (> or = 42 weeks) and 310 patients with normal term pregnancies (37 to < 42 weeks) were analyzed. The Gold Stat package was used for statistical coding and analysis.

RESULTS

There was no fetal morbidity or mortality among the two groups. However, the number of previous abortions were significantly higher in prolonged pregnancies compared with term pregnancies. Similarly, fetal and placental weights, labor induction and operative delivery rates were significantly higher in prolonged pregnancies. However, there were no significant differences between the patients who were induced and those who had spontaneous labor among the prolonged pregnancies.

CONCLUSIONS

There is no doubt that prolonged pregnancy may be associated with certain risks factors. However, there is no outcome variable to justify whether or not to induce those pregnancies which are prolonged.

The epidemiology of neonatal respiratory disease

The epidemiology of many conditions affecting the newborn infant is influenced by the health of the mother, prematurity and the effects of medical and obstetric management. In this review we have considered the role of each of these factors in seven respiratory conditions presenting in the newborn infant.

A controlled trial of amnioinfusion: the prevention of meconium aspiration in labour

The purpose of this study was to examine the effect of amnioinfusion on the incidence of meconium aspiration syndrome, perinatal asphyxia and obstetrical intervention rate amongst patients with moderate and thick meconium-stained liquor. A total of 112 patients were studied in a prospective fashion; 60 received amnioinfusion and 52 served as controls. We have shown that amnioinfusion is a simple, relatively inexpensive and safe procedure. It benefits the patient in terms of reduction in the likelihood of operative intervention (specifically Caesarean section) for fetal distress and improvement in neonatal outcome with reduced frequency of neonatal acidaemia.

Clinical significance of fetal heart rate patterns during labor. IX: Prolonged pregnancy

The intrapartum FHR and UC were recorded in a population of 707 consecutive cases of prolonged gestation looking for a characteristic pattern. There is no typical pattern for prolonged pregnancy. However, there are differences from preterm and term populations. There is a very high incidence of variable (55%) and late (17%) decelerations. These were seen more frequently among cases receiving oxytocin. Nearly 50% of C-sections had lates. Baseline alterations (tachycardia 26%, fixed 8%, and saltatory 17%) were often associated. Apgar scores < or = 6 at 1 minute were correlated with variable and late decelerations. However, acidemia (UA pH < or = 7.20) could not be predicted from FHR patterns because there was no correlation between low pH and clinical depression. Alarmingly a few fetuses in agonal state presented normal appearing tracings, or deteriorated rapidly without the usual indicative changes by FHR. All intrapartum or NND had this misleading pattern. In view of this unpredictable aberrant pattern as the only certain means to prevent these deaths, it is suggested that no pregnancy should be allowed to reach 294 days post LMP.

Maternal-fetal outcomes in prolonged pregnancy

The intrapartum fetal heart rate changes, type of labor, mode of delivery, and neonatal outcome were evaluated in 379 consecutive continuously monitored prolonged pregnancies (greater than 42 weeks by history and early examination). These represent only a fraction of the total prolonged gestation population. There were 56% multiparous women, 33% less than 20 years of age, and 95% with cephalic presentation. Oxytocin was given to 76% (48% induced, 28% enhanced). Delivery was by cesarean section in 13% of patients (9% of induced cases), and 15% had forceps deliveries. Fetal heart rate alterations were observed in high proportion. Cesarean section for cephalopelvic disproportion was indicated in 60% of operations, and 13% of the fetuses weighed greater than 4000 gm. Depression occurred in 15% of infants at 1 minute and in 4% at 5 minutes. Prolonged hospital stay was seen in 9%, and postmaturity syndrome in 19%. There were four perinatal deaths (two corrected). Active induction does not appear to increase the cesarean section rate. The durations of predelivery observation may be longer because the cervices are frequently unripe. There is a high incidence of fetal heart rate alterations. Induction appears justified as an active intervention to prevent some sudden unexplained deaths.

The value of amnioscopy in surveillance of postdate pregnancy

The accuracy and reliability of amnioscopy in detecting the presence of meconium in amniotic fluid and in predicting fetal distress were evaluated in 289 postdate pregnancies. Meconium-stained amniotic fluid tended to be associated with complications of pregnancy such as ABO incompatibility (p less than 0.05), the need for operative delivery (p less than 0.02), and fetal distress at birth (p less than 0.05). Amnioscopy failed to detect the presence of meconium antenatally in most cases (57%), and positive amnioscopy for meconium was unrelated to the incidence of fetal distress. When meconium was present, induction of labour was ineffective in reducing the incidence of fetal distress. Amnioscopy is not recommended for the monitoring of postdate pregnancies.

Fatal meconium aspiration syndrome occurring despite airway management considered appropriate

A combined obstetric-pediatric approach to tracheal toilet is said to prevent serious cases of the potentially fatal meconium aspiration syndrome. After delivery of the head a DeLee trap is used to suction the oropharynx and nasopharynx. Immediately following delivery, endotracheal suction is performed in an effort to remove any remaining meconium-stained amniotic fluid. Although routinely using this approach, we continue to have occasional cases of fatal meconium aspiration syndrome. Therefore, we reviewed the outcome of infants born through meconium-stained fluid. During a 5-year period, 1420 (15%) of 9299 live-born infants had meconium-stained fluid. Thirty (2.1%) of these 1420 developed meconium aspiration syndrome and 12 (40%) died; eight received a postmortem examination. Four had unequivocal evidence of meconium aspiration, two had large numbers of intra-alveolar squamous cells, and two had no evidence of aspiration. We conclude that aggressive airway management during and immediately after delivery does not always prevent fatal meconium aspiration syndrome.

The use of breast stimulation to prevent postdate pregnancy

Postdate pregnancy is estimated to occur in 3% to 12% of all gestations. Morbidity and mortality rates associated with this common obstetric problem are higher than those with term gestation. The incidence of fetal distress, birth injury, meconium aspiration, congenital malformations, macrosomia, and oligohydramnios is also greater in postdate pregnancy. We prospectively evaluated breast self-stimulation to determine its effect on the incidence of postdate pregnancy. Two hundred low-risk patients at 39 weeks' gestation were randomly assigned to either a control group or a breast-stimulation group. Results showed that breast stimulation reduced the number of pregnancies managed as postdates from 17 per 100 (17%) to five per 100 (5%) (p less than 0.01), a 70% reduction. It is concluded that breast stimulation in postdates pregnancies can decrease significantly the number of patients that must be monitored by biochemical or biophysical means.

The value of ultrasound measurement of amniotic fluid volume in the management of prolonged pregnancies

Ultrasound assessment of amniotic fluid volume was used to monitor 335 patients with prolonged pregnancy. Reduced amniotic fluid was diagnosed when no single vertical pool of amniotic fluid measured greater than 30 mm. Sixty-five patients with reduced amniotic fluid had labour induced while 270 patients with normal amniotic fluid were managed expectantly unless the cervix was favourable. Patients with reduced amniotic fluid had a statistically significant increase in meconium-stained amniotic fluid and growth-retarded babies and were more likely to require delivery by caesarean section for fetal distress. There were no perinatal deaths in the series and the perinatal outcome was satisfactory in both groups. Ultrasound measurement of amniotic fluid represents an effective discriminatory test in post-term pregnancy.

Conservative management of prolonged pregnancy using fetal heart rate monitoring only: a prospective study

Eighty patients with prolonged pregnancy were managed conservatively using outpatient non-stress testing as the only form of fetal monitoring; there was no excess perinatal mortality or morbidity. The 'at risk' fetus appeared to be predominantly within the 'postmature' group who pass meconium. Non-stress testing using this rigid regimen was an excellent screening test to identify the 'at risk' fetus and in this study had a zero false-negative rate. Probably only one in 20 post-term infants require induction for fetal indications.

Non-aggressive management of post-date pregnancies

A non-aggressive approach to the management of post-date pregnancies was tested in a clinical trial involving 156 patients who had reached 294 days of amenorrhea and had a pelvic score of 4 or less. Dates had been established with certainty in each case. In half of the patients (the study group) no time limit was imposed on the pregnancy, but the women were checked at frequent intervals for any increase in pelvic score and for changes in any of the following: fetal movement count recorded daily by the mother, an oxytocin challenge test, and amnioscopy. The pregnancy ended either through spontaneous contractions or through surgical induction carried out because of a change in any one of the parameters or an increase above 4 in the pelvic score. In the 78 control patients labor was induced surgically on day 294, even if the pelvic score was low. In the study group, labor started spontaneously in 52 patients; labor was induced in 17 women after they showed an elevated pelvic score, in 7 because of a pathologic parameter and in one because a mild pre-eclampsia developed. There were 7 cesarean sections in the study group compared with 16 in the control group (P less than 0.05). The average duration of labor was 6.7 h in the study group, compared with 9.4 h in the control (P less than 0.01). There was no significant difference between the two groups with regard to meconium staining during labor, pathologic fetal heart rate, or the 5 min Apgar score. In the study group there was one neonatal death as a result of severe congenital heart disease, and in the control group one infant died due to asphyxia. It is concluded that conservative management of prolonged pregnancies, with close supervision, gives better results than routine induction of labor at 42 wk. The importance of the pelvic score as an indication for induction is stressed. A protocol has been developed which can be used in cases of uncertain dates as well.

Comparison of antepartum testing schemes for the management of the postdate pregnancy

We analyzed the outcome results of 583 postdate pregnancies managed prospectively by one of three antepartum testing schemes, each predicated on the nonstress test. In scheme 1, we relied upon the contraction stress test for evaluation of the nonreactive nonstress test. In scheme 2, we used a modified biophysical profile to evaluate the nonreactive nonstress test. In addition, patients were tested semiweekly. In scheme 3, we added routine weekly ultrasound evaluation of amniotic fluid volume to scheme 2. Only in scheme 3 did we induce labor for decreased amniotic fluid volume or fetal cardiac decelerations irrespective of reactivity. The incidence of fetal distress, perinatal mortality, and perinatal morbidity was increased in babies with decelerations or decreased amniotic fluid volume. Nevertheless, outcome results in scheme 2 were improved over those with scheme 1 and were best with scheme 3. These results suggest a benefit to both semiweekly testing and liberalized criteria for intervention in postdate pregnancies. We also compared the outcome results of scheme 3 with those reported for schemes in which the weekly contraction stress test was used as the primary form of surveillance. We found the outcome results comparable in that both schemes showed minimal mortality and morbidity statistics but high intervention rates (25% to 30%). Differences in methodology and test criteria, however, make such comparisons less than ideal.

Intrapartum assessment of the postdate fetus

Continuous monitoring of fetal heart rate (FHR) and routine sampling of fetal scalp blood were utilized to evaluate the intrapartum performance of 82 fetuses of postdates pregnancies. A comparison was made between this group and 260 term pregnancies. The incidences of abnormal FHR patterns were not different between the postdates group and the control group. All of the postdates neonates with low 5 minute Apgar scores had passed meconium. The mean pH values of the postdates fetuses with meconium were significantly lower than those of the control group at each sampling interval (i.e., early labor, late labor, and umbilical artery). Those fetuses with thick meconium had significantly lower pH values in late labor than did those with thin meconium. Continuous electronic FHR monitoring is recommended for intrapartum surveillance of all postdates patients. Because of the increased incidence of fetal acidosis in the presence of thick meconium, sampling of fetal scalp blood is not unreasonable even with a normal FHR pattern.

Urinary estrogens in postterm pregnancy

A 40-month retrospective review of 677 postterm pregnancies was undertaken to determine the usefulness of 24-hour urinary estrogen per gram of creatinine (E/Cr) in monitoring such pregnancies. The cutoff value between normal and low E/Cr values was chosen at the tenth percentile (18 mg/gm). The corrected perinatal mortality rate (PMR) in post-term pregnancies with normal E/Cr was 0.23% (1/426) and was not different from that at term (0.23%; 4/1,775). However, in post-term pregnancies with low E/Cr, the corrected PMR was 9.2% (4/43), representing a 40-fold increase (P less than 0.001). The incidence of fetal distress was also significantly higher in patients with low E/Cr (57%) than in those with normal E/Cr (5.5%; P less than 0.001). It was worrisome to note that three of four stillborn infants had antepartum fetal heart testing within 4 days, which indicated fetal well-being. The E/Cr appears to be a reliable test for identifying those postterm pregnancies at risk that might benefit from obstetric intervention.

Postdate pregnancy: utilization of contraction stress testing for primary fetal surveillance

Six hundred seventy-nine postdate study patients surveyed with a contraction stress test (CST) protocol had no perinatal deaths and no greater morbidity than that found in a 500-patient normal term control population. However, the postdate study did have a significantly increased risk of intrapartum fetal distress, meconium-stained amniotic fluid, macrosomia, and cesarean section for both failed progress of labor and fetal distress. Among the postdate study group there was a high incidence of patients with abnormal CST results (39%); these patients with abnormal CST results were at increased risk for subsequent intrapartum fetal distress. Seventy-five percent of the postdate study patients entered labor spontaneously and delivery was elected because of abnormal CST results in only 5.4%. The data presented here support the use of contraction stress testing for primary surveillance of the prolonged pregnancy and they suggest that only one in 20 patients past 42 weeks' gestation will require intervention for fetal indications with this approach.