Trends in labor induction in the United States: is it true that what goes up must come down?

Outpatient cervical ripening with balloon catheters: A Bayesian network meta-analysis of randomized controlled trials

BACKGROUND

One in four labors are induced. The process of cervical ripening can be lengthy and pre-labor hospitalization is required. Outpatient cervical ripening can be an attractive alternative.

OBJECTIVES

To evaluate the efficacy and safety of outpatient cervical ripening with a balloon catheter compared with inpatient balloon catheter or prostaglandin E2 (PGE2).

SEARCH STRATEGY

The PubMed, MEDLINE, Embase, ClinicalTrials.gov, and Cochrane Library databases were searched from their inception to October 15, 2022.

SELECTION CRITERIA

Randomized controlled trials comparing the outpatient balloon catheter with inpatient balloon catheter or inpatient PGE2 for term cervical ripening.

DATA COLLECTION AND ANALYSIS

Bayesian network meta-analysis was performed. The primary outcome was the cesarean delivery rate. The secondary outcomes included instrumental delivery, the time from intervention-to-birth, oxytocin augmentation, total hospital duration, and maternal/neonatal adverse events.

MAIN RESULTS

Twenty-nine randomized controlled trials with a total of 6004 participants were identified. No difference in the cesarean delivery rate was revealed among the three interventions. Compared with inpatient balloon catheter, outpatient balloon catheter had shorter total hospital duration (mean difference -8.58, 95% confidence interval -17.02 to -1.10). No differences were revealed in the time from intervention-to-birth, instrumental delivery, postpartum hemorrhage, 5-min Apgar score less than 7, umbilical cord arterial pH less than 7.1, and neonatal intensive care unit admission among the three interventions.

CONCLUSIONS

Outpatient balloon catheter in low-risk term pregnancies is an available option that could be considered for cervical ripening. The safety and effectiveness are comparable to inpatient cervical ripening methods.

MEchanical DIlatation of the Cervix-- in a Scarred uterus (MEDICS): the study protocol of a randomised controlled trial comparing a single cervical catheter balloon and prostaglandin PGE2 for cervical ripening and labour induction following caesarean delivery

INTRODUCTION

Labour induction in women with a previous caesarean delivery currently uses vaginal prostaglandin E2 (PGE2), which carries the risks of uterine hyperstimulation and scar rupture. We aim to compare the efficacy of mechanical labour induction using a transcervically applied Foley catheter balloon (FCB) with PGE2 in affected women attempting trial of labour after caesarean (TOLAC).

METHODS AND ANALYSIS

This single-centre non-inferiority prospective, randomised, open, blinded-endpoint study conducted at an academic maternity unit in Singapore will recruit a total of 100 women with one previous uncomplicated caesarean section and no contraindications to vaginal delivery. Eligible consented participants with term singleton pregnancies and unfavourable cervical scores (≤5) requiring labour induction undergo stratified randomisation based on parity and are assigned either FCB (n=50) or PGE2 (n=50). Treatments are applied for up to 12 hours with serial monitoring of the mother and the fetus and serial assessment for improved cervical scores. If the cervix is still unfavourable, participants are allowed a further 12 hours' observation for cervical ripening. Active labour is initiated by amniotomy at cervical scores of ≥6. The primary outcome is the rate of change in the cervical score, and secondary outcomes include active labour within 24 hours of induction, vaginal delivery, time-to-delivery interval and uterine hyperstimulation. All analyses will be intention-to-treat. The data generated in this trial may guide a change in practice towards mechanical labour induction if this proves efficient and safer for women attempting TOLAC compared with PGE2, to improve labour management in this high-risk population.

ETHICS AND DISSEMINATION

Ethical approval is granted by the Domain Specific Review Board (Domain D) of the National Healthcare Group, Singapore. All adverse events will be reported within 24 hours of notification for assessment of causality. Data will be published and will be available for future meta-analyses.

TRIAL REGISTRATION NUMBER

NCT03471858; Pre-results.

Pharmacological and mechanical interventions for labour induction in outpatient settings

BACKGROUND

Induction of labour is carried out for a variety of indications and using a range of methods. For women at low risk of pregnancy complications, some methods of induction of labour or cervical ripening may be suitable for use in outpatient settings.

OBJECTIVES

To examine pharmacological and mechanical interventions to induce labour or ripen the cervix in outpatient settings in terms of effectiveness, maternal satisfaction, healthcare costs and, where information is available, safety.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 November 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining outpatient cervical ripening or induction of labour with pharmacological agents or mechanical methods. Cluster trials were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

This updated review included 34 studies of 11 different methods for labour induction with 5003 randomised women, where women received treatment at home or were sent home after initial treatment and monitoring in hospital.Studies examined vaginal and intracervical prostaglandin E₂ (PGE₂), vaginal and oral misoprostol, isosorbide mononitrate, mifepristone, oestrogens, amniotomy and acupuncture, compared with placebo, no treatment, or routine care. Trials generally recruited healthy women with a term pregnancy. The risk of bias was mostly low or unclear, however, in 16 trials blinding was unclear or not attempted. In general, limited data were available on the review's main and additional outcomes. Evidence was graded low to moderate quality. 1. Vaginal PGE₂ versus expectant management or placebo (5 studies)Fewer women in the vaginal PGE₂ group needed additional induction agents to induce labour, however, confidence intervals were wide (risk ratio (RR) 0.52, 95% confidence interval (CI) 0.27 to 0.99; 150 women; 2 trials). There were no clear differences between groups in uterine hyperstimulation (with or without fetal heart rate (FHR) changes) (RR 3.76, 95% CI 0.64 to 22.24; 244 women; 4 studies; low-quality evidence), caesarean section (RR 0.80, 95% CI 0.49 to 1.31; 288 women; 4 studies; low-quality evidence), or admission to a neonatal intensive care unit (NICU) (RR 0.32, 95% CI 0.10 to 1.03; 230 infants; 3 studies; low-quality evidence).There was no information on vaginal birth within 24, 48 or 72 hours, length of hospital stay, use of emergency services or maternal or caregiver satisfaction. Serious maternal and neonatal morbidity or deaths were not reported. 2. Intracervical PGE₂ versus expectant management or placebo (7 studies) There was no clear difference between women receiving intracervical PGE₂ and no treatment or placebo in terms of need for additional induction agents (RR 0.98, 95% CI 0.74 to 1.32; 445 women; 3 studies), vaginal birth not achieved within 48 to 72 hours (RR 0.83, 95% CI 0.68 to 1.02; 43 women; 1 study; low-quality evidence), uterine hyperstimulation (with FHR changes) (RR 2.66, 95% CI 0.63 to 11.25; 488 women; 4 studies; low-quality evidence), caesarean section (RR 0.90, 95% CI 0.72 to 1.12; 674 women; 7 studies; moderate-quality evidence), or babies admitted to NICU (RR 1.61, 95% CI 0.43 to 6.05; 215 infants; 3 studies; low-quality evidence). There were no uterine ruptures in either the PGE₂ group or placebo group.There was no information on vaginal birth not achieved within 24 hours, length of hospital stay, use of emergency services, mother or caregiver satisfaction, or serious morbidity or neonatal morbidity or perinatal death. 3. Vaginal misoprostol versus placebo (4 studies)One small study reported on the rate of perinatal death with no clear differences between groups; there were no deaths in the treatment group compared with one stillbirth (reason not reported) in the control group (RR 0.34, 95% CI 0.01 to 8.14; 77 infants; 1 study; low-quality evidence).There was no clear difference between groups in rates of uterine hyperstimulation with FHR changes (RR 1.97, 95% CI 0.43 to 9.00; 265 women; 3 studies; low-quality evidence), caesarean section (RR 0.94, 95% CI 0.61 to 1.46; 325 women; 4 studies; low-quality evidence), and babies admitted to NICU (RR 0.89, 95% CI 0.54 to 1.47; 325 infants; 4 studies; low-quality evidence).There was no information on vaginal birth not achieved within 24, 48 or 72 hours, additional induction agents required, length of hospital stay, use of emergency services, mother or caregiver satisfaction, serious maternal, and other neonatal, morbidity or death.No substantive differences were found for other comparisons. One small study found that women who received oral misoprostol were more likely to give birth within 24 hours (RR 0.65, 95% CI 0.48 to 0.86; 87 women; 1 study) and were less likely to require additional induction agents (RR 0.60, 95% CI 0.37 to 0.97; 127 women; 2 studies). Women who received mifepristone were also less likely to require additional induction agents (average RR 0.59, 95% CI 0.37 to 0.95; 311 women; 4 studies; I² = 74%); however, this result should be interpreted with caution due to high heterogeneity. One trial each of acupuncture and outpatient amniotomy were included, but few review outcomes were reported.

AUTHORS' CONCLUSIONS

Induction of labour in outpatient settings appears feasible and important adverse events seem rare, however, in general there is insufficient evidence to detect differences. There was no strong evidence that agents used to induce labour in outpatient settings had an impact (positive or negative) on maternal or neonatal health. There was some evidence that compared to placebo or no treatment, induction agents administered on an outpatient basis reduced the need for further interventions to induce labour, and shortened the interval from intervention to birth.We do not have sufficient evidence to know which induction methods are preferred by women, the interventions that are most effective and safe to use in outpatient settings, or their cost effectiveness. Further studies where various women-friendly outpatient protocols are compared head-to-head are required. As part of such work, women should be consulted on what sort of management they would prefer.

Population attributable risks of neurobehavioral disorders due to low birth weight in US children

BACKGROUND

The prevalence of low birth weight (LBW) and neurobehavioral disorders (N) has increased over the last three decades. However, it is unclear how many excess cases of ND can be attributed to LBW among U.S. children. The objectives of this study were to a) determine the association between LBW and ND including attention deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), behavior and conduct disorder (BCD) and learning disability (LD); and b) determine the population attributable risk (PAR) of these disorders due to LBW.

METHODS

Study subjects were a nationally representative cross-sectional sample of 85,637 children ages 2 to 17 years old who participated in the 2011 National Survey of Children's Health. Birth weight and ND were reported by parents.

RESULTS

LBW accounted for 6.0% (95% confidence interval [CI] 2.3-10.4) of all ASD cases, 2.4% (CI 0.1-5.1) of BCD, and 6.8% (CI 4.8-9.0) of LD among the study population. There was not a significant association between LBW and ADHD. The percentages of these ND due to LBW were found to be higher among those who were pre-term and among ethnic minority groups.

CONCLUSIONS

Based on our results and given that over 8% of U.S. children are born with LBW, with higher rates among minorities and preterm births, prospective planning for neurobehavioral services is warranted. Efforts to reduce ND in children align with national efforts to reduce LBW.

A retrospective cohort study of mode of delivery among public and private patients in an integrated maternity hospital setting

OBJECTIVE

To examine the associations between mode of delivery and public versus privately funded obstetric care within the same hospital setting.

DESIGN

Retrospective cohort study.

SETTING

Urban maternity hospital in Ireland.

POPULATION

A total of 30 053 women with singleton pregnancies who delivered between 2008 and 2011.

METHODS

The study population was divided into those who booked for obstetric care within the public (n=24 574) or private clinics (n=5479). Logistic regression analyses were performed to examine the associations between operative delivery and type of care, adjusting for potential confounding factors.

MAIN OUTCOME MEASURES

Caesarean section (scheduled or emergency), operative vaginal delivery (vacuum or forceps), indication for caesarean section as classified by the operator.

RESULTS

Compared with public patients, private patients were more likely to be delivered by caesarean section (34.4% vs 22.5%, OR 1.81; 95% CI 1.70 to 1.93) or operative vaginal delivery (20.1% vs 16.5%, OR 1.28; 95% CI 1.19 to 1.38). The greatest disparity was for scheduled caesarean sections; differences persisted for nulliparous and parous women after controlling for medical and social differences between the groups (nulliparous 11.9% vs 4.6%, adjusted (adj) OR 1.82; 95% CI 1.49 to 2.24 and parous 26% vs 12.2%, adj OR 2.08; 95% CI 1.86 to 2.32). Scheduled repeat caesarean section accounted for most of the disparity among parous patients. Maternal request per se was an uncommonly reported indication for caesarean section (35 in each group, p<0.000).

CONCLUSIONS

Privately funded obstetric care is associated with higher rates of operative deliveries that are not fully accounted for by medical or obstetric risk differences.

Delivery outcomes for nulliparous women at the extremes of maternal age - a cohort study

OBJECTIVE

To examine the associations between extremes of maternal age (≤17 years or ≥40 years) and delivery outcomes.

DESIGN

Retrospective cohort study.

SETTING

Urban maternity hospital in Ireland.

POPULATION

A total of 36 916 nulliparous women with singleton pregnancies who delivered between 2000 and 2011.

METHODS

The study population was subdivided into five maternal age groups based on age at first booking visit: ≤17 years, 18-19 years, 20-34 years, 35-39 years and women aged ≥40 years. Logistic regression analyses were performed to examine the associations between extremes of maternal age and delivery outcomes, adjusting for potential confounding factors.

MAIN OUTCOME MEASURES

Preterm birth, admission to the neonatal unit, congenital anomaly, caesarean section.

RESULTS

Compared with maternal age 20-34 years, age ≤17 years was a risk factor for preterm birth (adjusted odds ratio [adjOR] 1.83, 95% confidence interval [95% CI] 1.33-2.52). Babies born to mothers ≥40 years were more likely to require admission to the neonatal unit (adjOR 1.35, 95% CI 1.06-1.72) and to have a congenital anomaly (adjOR 1.71, 95% CI 1.07-2.76). The overall caesarean section rate in nulliparous women was 23.9% with marked differences at the extremes of maternal age; 10.7% at age ≤17 years (adjOR 0.46, 95% CI 0.34-0.62) and 54.4% at age ≥40 years (adjOR 3.24, 95% CI 2.67-3.94).

CONCLUSIONS

Extremes of maternal age need to be recognised as risk factors for adverse delivery outcomes. Low caesarean section rates in younger women suggest that a reduction in overall caesarean section rates may be possible.

The rise in singleton preterm births in the USA: the impact of labour induction

OBJECTIVE

To assess the extent to which increased rates of labour induction and caesarean section have contributed to the recent rise in preterm birth.

DESIGN

National birth cohort study.

SETTING

USA.

POPULATION AND SAMPLE

Singleton live births, with primary analysis based on non-Hispanic white women.

METHODS

Ecological study based on the 50 states and the District of Columbia during two time periods 10 years apart: 1992-94 and 2002-04.

MAIN OUTCOME MEASURE

Preterm birth (live birth <37 completed weeks of gestation), based on an algorithm combining menstrual and clinical estimates of gestational age.

RESULTS

The state-level ecological analysis among non-Hispanic white women showed that the change in preterm birth rate from 1992-94 to 2002-04 was significantly associated with the change in rate of labour induction (r = 0.50, 95% CI 0.26-0.68), but not with the change in rate of caesarean delivery (r = -0.06, 95% CI -0.33 to 0.22). Weaker but otherwise similar associations with labour induction were observed in Hispanic women and in non-Hispanic black women.

CONCLUSIONS

Increasing use of labour induction is probably an important cause of the observed increased rate in preterm birth.

Vaginal Misoprostol vs Vaginal Misoprostol With Estradiol for Labor Induction: A Prospective Double Blind Study

OBJECTIVE

To compare the safety and effectiveness of vaginal misoprostol with combined vaginal misoprostol and estradiol for induction of labor in unfavorable cervix.

METHOD

A prospective study was carried out from Jan 2008 to Jul 2008 on total of 90 women with unfavorable cervix (Bishop's score was <5) and gestation >36 weeks with clinical indication for induction of labor. They were randomly assigned to receive either vaginal misoprostol 25 μg alone or vaginal misoprostol 25 μg with vaginal estradiol 50 μg. Misoprostol alone was repeated every 3 h in both groups till ripening of cervix (Bishop's score was = 8) and establishment of active labor.

RESULTS

Main indications were post dated pregnancies (period of gestation >41 weeks) and pregnancy induced hypertension. Age, parity and mode of delivery were not significantly different. No significant difference was found in pre induction Bishop's score, fetal outcome and maternal complications. However, doses of misoprostol required for cervical ripening (p = 0.017), time required for cervical ripening (p = 0.042), time required for starting of active labor (p = 0.017) and time required for delivery in vaginal delivery cases (p = 0.047) were found significantly less in combined estradiol and misoprostol group.

CONCLUSION

Estradiol acts synergistically with misoprostol vaginally and significantly hastens the process of cervical ripening, initiation of active labor and vaginal delivery.

Timing of delivery and pregnancy outcomes among laboring nulliparous women

OBJECTIVE

The objective of the study was to compare pregnancy outcomes by completed week of gestation after 39 weeks with outcomes at 39 weeks.

STUDY DESIGN

Secondary analysis of a multicenter trial of fetal pulse oximetry in spontaneously laboring or induced nulliparous women at a gestation of 36 weeks or longer. Maternal outcomes included a composite (treated uterine atony, blood transfusion, and peripartum infections) and cesarean delivery. Neonatal outcomes included a composite of death, neonatal respiratory and other morbidities, and neonatal intensive care unit admission.

RESULTS

Among the 4086 women studied, the risks of the composite maternal outcome (P value for trend < .001), cesarean delivery (P < .001), and composite neonatal outcome (P = .047) increased with increasing gestational age from 39 to 41 or more completed weeks. Adjusted odds ratios (95% confidence interval) for 40 and 41 or more weeks, respectively, compared with 39 weeks were 1.29 (1.03-1.64) and 2.05 (1.60-2.64) for composite maternal outcome, 1.28 (1.05-1.57) and 1.75 (1.41-2.16) for cesarean delivery, and 1.25 (0.86-1.83) and 1.37 (0.90-2.09) for composite neonatal outcome.

CONCLUSION

Risks of maternal morbidity and cesarean delivery but not neonatal morbidity increased significantly beyond 39 weeks.

Mothers' level of education and childbirth interventions: A population-based study in Flanders, Northern Belgium

BACKGROUND

  Interventions to influence the time and way to be born have been a global concern for decades. Yet, limited information is available on what drives these interventions and their variation in frequency among countries, institutions, and practitioners. The objective of this study was to examine to what extent first-time mothers' educational achievement contributes to the frequency of childbirth interventions.

METHODS

  Childbirth interventions, including induction of labor, cesarean section, instrumental delivery, and epidural analgesia, registered by the Flemish Study Center for Perinatal Epidemiology for Belgian-born nulliparous women from 1999 to 2006, were linked to the level of maternal education, recorded by the Belgian civil birth registration. Education was divided into four levels based on the highest diploma attained and adjusted for marital and occupational status.

RESULTS

  Frequencies of all interventions were inversely related to the level of maternal education. The effect remained after adjustment for birth year, maternal age, marital status, occupation, infant birthweight, gestational age, assisted conception, and type of hospital. Effect sizes between highest and lowest levels of education were relatively small for operative (31% vs 36%) and instrumental vaginal birth (20.7% vs 22.3%) compared with "initiated delivery" (defined as labor induction and prelabor cesarean section; 30.2% vs 40.3%) and epidural analgesia (66.8% vs 78.0%). The educational gradient in initiated delivery occurred at all gestational ages, contributing to lower gestational age and lower birthweight of term infants with decreasing levels of education.

CONCLUSIONS

  In an affluent society with universal and equitable access to maternity care, the more educated women are, the more likely they are to have a spontaneous labor and spontaneous birth without intervention. (BIRTH 38:3 September 2011).

Late pregnancy complications can affect risk estimates of elective induction of labor

OBJECTIVE

Multiple observational studies have emphasized the increased risk of elective induction versus spontaneous labor. We estimated the risks of elective induction before 39 weeks compared to expectant management.

METHODS

Using a single institution's delivery data (1996-2004), we identified women with uncomplicated term gestations who underwent elective induction before 39 weeks (Early Induction Group). A comparison group of women eligible for elective induction before 39 weeks but who were managed expectantly was created by identifying the remaining deliveries ≥ 39 weeks and excluding women with "established" pregnancy complications such as diabetes or heart disease (Expectant Management Group), but retaining women with complications that may have developed while waiting, e.g. gestational hypertension or abruption.

RESULTS

Pregnancies in the Early Induction Group were generally not at increased risk for morbidity when compared to the entire Expectant Management Group, in whom 49% developed pregnancy complications or went postdates. These pregnancies had poorer maternal and neonatal outcomes when compared to patients who remained uncomplicated with spontaneous labor onset, thus reducing the overall benefit of expectant management.

CONCLUSIONS

Failure to account for the large proportion of women who develop late pregnancy complications can falsely elevate the estimated risk of elective induction prior to 39 weeks.

Labor induction and the risk of a cesarean delivery among nulliparous women at term

OBJECTIVE

To estimate the association of labor induction with the risk of a cesarean delivery for nulliparous women presenting at term at a regional hospital.

METHODS

This was a retrospective cohort study of cesarean delivery among nulliparous women delivering a live, singleton, vertex pregnancy at term. We used clinical data from electronic hospital obstetric records at a large, regional, obstetric hospital, approximating a population-based cohort. Multivariable logistic regression was used to explore risk factors associated with cesarean delivery, and the fraction of cesarean deliveries attributable to the use of labor induction was estimated.

RESULTS

From a cohort of 24,679 women, 7,804 met inclusion criteria. Labor induction was used in 43.6% of cases, 39.9% of which were elective. Use of labor induction was associated with an increased odds of cesarean delivery (crude odds ratio 2.67, 2.40-2.96) and the association remained significant (adjusted odds ratio 1.93, 1.71-2.2) after adjustment for maternal demographic characteristics, medical risk, and pregnancy complications. The contribution of labor induction to cesarean delivery in this cohort was estimated to be approximately 20%.

CONCLUSION

Labor induction is significantly associated with a cesarean delivery among nulliparous women at term for those with and without medical or obstetric complications. Reducing the use of elective labor induction may lead to decreased rates of cesarean delivery for a population.

LEVEL OF EVIDENCE

II.

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.

Different methods for the induction of labour in outpatient settings

BACKGROUND

Induction of labour is carried out for a variety of indications and using a range of pharmacological, mechanical and other methods. For women at low risk, some methods of induction of labour may be suitable for use in outpatient settings.

OBJECTIVES

To examine pharmacological and mechanical interventions to induce labour in outpatient settings in terms of feasibility, effectiveness, maternal satisfaction, healthcare costs and, where information is available, safety. The review complements existing reviews on labour induction examining effectiveness and safety.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2009) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining outpatient cervical ripening or induction of labour with pharmacological agents or mechanical methods.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed eligible papers for risk of bias. We checked all data after entry into review manager software.

MAIN RESULTS

We included 28 studies with 2616 women examining different methods of induction of labour where women received treatment at home or were sent home after initial treatment and monitoring in hospital.Studies examined vaginal and intracervical PGE(2), vaginal and oral misoprostol, isosorbide mononitrate, mifepristone, oestrogens, and acupuncture. Overall, the results demonstrate that outpatient induction of labour is feasible and that important adverse events are rare. There was no strong evidence that agents used to induce labour in outpatient settings had an impact (positive or negative) on maternal or neonatal health. There was some evidence that, compared to placebo or no treatment, induction agents reduced the need for further interventions to induce labour, and shortened the interval from intervention to birth. We were unable to pool results on outcomes relating to progress in labour as studies tended to measure a very broad range of outcomes.There was no evidence that induction agents increased interventions in labour such as operative deliveries. Only two studies provided information on women's views about the induction process, and overall there was very little information on the costs to health service providers of different methods of labour induction in outpatient settings.

AUTHORS' CONCLUSIONS

Induction of labour in outpatient settings appears feasible. We do not have sufficient evidence to know which induction methods are preferred by women, or the interventions that are most effective and safe to use in outpatient settings.

Decreased term and postterm birthweight in the United States: impact of labor induction

OBJECTIVE

We sought to assess recent trends in falling mean birthweight (BW) and gestational age (GA) among US non-Hispanic white singleton live births >or=37 weeks of gestation and the contribution of increased rates of induction to these trends.

STUDY DESIGN

This was an ecological study based on US vital statistics from 1992 through 2003.

RESULTS

From 1992 through 2003, mean BW fell by 37 g, mean GA by 3 days, and macrosomia rates by 25%. Rates of induction nearly doubled from 14% to 27%. Our ecological state-level analysis showed that the increased rate of induction was significantly associated with reduced mean BW (r = -0.54; 95% confidence interval [CI], -0.71 to -0.29), mean GA (r = -0.44; 95% CI, -0.65 to -0.17), and rate of macrosomia (r = -0.55; 95% CI, -0.74 to -0.32).

CONCLUSION

Increasing use of induction is a likely cause of the observed recent declines in BW and GA. The impact of these trends on infant and long-term health warrants attention and investigation.

Gestational age differences in health and development among young Swedish men born at term

BACKGROUND

Although increased morbidity and mortality associated with pre-term birth and restricted fetal growth have been extensively studied, relatively little is known about variations in health outcomes among term births, because they are often assumed to be homogeneous.

METHODS

We examined variations in height, body mass index (BMI), systolic and diastolic blood pressure (SBP and DBP), and intellectual performance by gestational age and fetal 'growth' (birth weight for gestational age) among young Swedish men born at term (37-41 weeks of gestation). We also compared the magnitude of associations among 314,642 men from different families and among 72,212 full brothers from 35,215 families to assess whether the associations are explained by familial factors shared by siblings.

RESULTS

Gestational age in completed weeks was positively associated with height [0.11 cm, 95% confidence interval (CI): 0.09-0.13] and intellectual performance (0.01, 95% CI: 0.00-0.02) and negatively associated with SBP (-0.28 mmHg, 95% CI: -0.33 to -0.24), after controlling for birth weight, maternal age at the men's birth, parity, family socio-economic position and family structure. The associations with height and SBP were observed also among brothers within families, suggesting that they are not explained by shared family characteristics. However, the positive association between gestational age and intellectual performance was no longer present within families. Birth weight for gestational age (z-score) was positively associated with height, BMI and intellectual performance and negatively associated with SBP. These associations were robust within families.

CONCLUSIONS

Among young men born at term, fetal growth and even gestational age are independently associated with adult size, BP and cognitive ability. The extent to which shared family characteristics explain the associations varies across outcomes.

Variation in child cognitive ability by week of gestation among healthy term births

The authors investigated variations in cognitive ability by gestational age among 13,824 children at age 6.5 years who were born at term with normal weight, using data from a prospective cohort recruited in 1996-1997 in Belarus. The mean differences in the Wechsler Abbreviated Scales of Intelligence were examined by gestational age in completed weeks and by fetal growth after controlling for maternal and family characteristics. Compared with the score for those born at 39-41 weeks, the full-scale intelligence quotient (IQ) score was 1.7 points (95% confidence interval (CI): -2.7, -0.7) lower in children born at 37 weeks and 0.4 points (95% CI: -1.1, 0.02) lower at 38 weeks after controlling for confounders. There was also a graded relation in postterm children: a 0.5-points (95% CI: -2.6, 1.6) lower score at 42 weeks and 6.0 points (95% CI: -15.1, 3.1) lower at 43 weeks. Compared with children born large for gestational age (>90th percentile), children born small for gestational age (<10th percentile) had the lowest IQ, followed by those at the 10th-50th percentile and those at the >50th-90th percentile. These findings suggest that, even among healthy children born at term, cognitive ability at age 6.5 years is lower in those born at 37 or 38 weeks and those with suboptimal fetal growth.

Variations in mortality and morbidity by gestational age among infants born at term

OBJECTIVE

To examine the risks of infant death and neonatal morbidity by week of gestation at term.

STUDY DESIGN

National U.S. birth cohort study on the basis of singleton live births in 1995-2001 at 37 to 41 completed weeks gestational age (GA), with exclusion of congenital anomalies. Main outcomes included neonatal, postneonatal, and cause-specific infant death; low-Apgar score at 5 minutes; receipt of neonatal mechanical ventilation >or=30 minutes; neonatal seizures; birth injury; and meconium aspiration syndrome. To reduce confounding by indication, we carried out a secondary analysis restricted to low-risk deliveries.

RESULTS

In non-Hispanic white women, the mortality rate decreased with increasing GA from 37 to 39 weeks, remained stable from 39 to 40 weeks, and then (for neonatal death) increased at 41 weeks. Rates of low 5-minute Apgar score and mechanical ventilation showed a U-shaped relation across term GAs, and rates of meconium aspiration syndrome and birth injury rose with increasing GA. Results were similar among infants born to low-risk mothers and in non-Hispanic black women.

CONCLUSIONS

Term infants show considerable heterogeneity across gestational age in neonatal and late infant outcomes, even when born to mothers at low risk. Recent trends toward earlier labor induction may have adverse health impacts.

Trends in mode of delivery during 1984-2003: can they be explained by pregnancy and delivery complications?

OBJECTIVES

To describe trends in mode of delivery, to identify significant factors which affected mode of delivery, and to describe how these factors and their impact have changed over time.

DESIGN

Total population birth cohort.

SETTING

Western Australia 1984-2003.

PARTICIPANTS

The analysis was restricted to all singleton infants delivered at 37-42 weeks of gestation with a cephalic presentation (n = 432,327).

METHODS

Logistic regression analyses were undertaken to estimate significant independent risk factors separately for elective and emergency caesarean sections compared with vaginal delivery (spontaneous and instrumental), adjusting for potential confounding variables.

MAIN OUTCOME MEASURES

Trends in mode of delivery, demographic factors, and pregnancy and delivery complications. Estimated likelihood of elective caesarean section compared with vaginal delivery and emergency caesarean section compared with vaginal delivery.

RESULTS

Between 1984-88 and 1999-2003, the likelihood of women having an elective caesarean section increased by a factor of 2.35 times (95% CI 2.28-2.42) and the likelihood of an emergency caesarean section increased 1.89 times (95% CI 1.83-1.96). These caesarean section rate increases remained even after adjustment for their strong associations with many sociodemographic factors, obstetric risk factors, and obstetric complications. Rates of caesarean section were higher in older mothers, especially those older than 40 years of age (elective caesarean section, OR 5.42 [95% CI 4.88-6.01]; emergency caesarean section, OR 2.67 [95% CI 2.39-2.97]), and in nulliparous women (elective caesarean section, OR 1.54 [95% CI 1.47-1.61]; emergency caesarean section, OR 3.61 [95% CI 3.47-3.76]).

CONCLUSIONS

Our data show significant changes in mode of delivery in Western Australia from 1984-2003, with an increasing trend in both elective and emergency caesarean section rates that do not appear to be explained by increased risk or indication.

Amniotic-fluid embolism and medical induction of labour: a retrospective, population-based cohort study

BACKGROUND

Amniotic-fluid embolism is a rare, but serious and often fatal maternal complication of delivery, of which the cause is unknown. We undertook an epidemiological study to investigate the association between amniotic-fluid embolism and medical induction of labour.

METHODS

We used a population-based cohort of 3 million hospital deliveries in Canada between 1991 and 2002 to assess the associations between overall and fatal rates of amniotic-fluid embolism and medical and surgical induction, maternal age, fetal presentation, mode of delivery, and pregnancy and labour complications.

FINDINGS

Total rate of amniotic-fluid embolism was 14.8 per 100,000 multiple-birth deliveries and 6.0 per 100,000 singleton deliveries (odds ratio 2.5 [95% CI 0.9-6.2]). Of the 180 cases of amniotic-fluid embolism in women with singleton deliveries during the study period, 24 (13%) were fatal. We saw no significant temporal increase in occurrence of amniotic-fluid embolism for total or fatal cases. Medical induction of labour nearly doubled the risk of overall cases of amniotic-fluid embolism (adjusted odds ratio 1.8 [1.3-2.7]), and the association was stronger for fatal cases (crude odds ratio 3.5 [1.5-8.4]). Maternal age of 35 years or older, caesarean or instrumental vaginal delivery, polyhydramnios, cervical laceration or uterine rupture, placenta previa or abruption, eclampsia, and fetal distress were also associated with an increased risk.

INTERPRETATION

Medical induction of labour seems to increase the risk of amniotic-fluid embolism. Although the absolute excess risk is low, women and physicians should be aware of this risk when making decisions about elective labour induction.

Back to the future? A critical commentary on the 2003 U.S. National standard certificate of live birth

Vital statistics documents for the United States have been revised approximately decennially throughout the past century. In this commentary we review the contents of the 2003 revision of the national standard certificate of live birth, focusing on changes from the certificates in use nationally since 1989, and identifying strengths and weaknesses of key data elements. Additional federal-state partnership funding is imperative to support the transition to the new standard certificates, and to ensure a focus on data quality at the state and national levels.

Induction of labour at the start of the new millennium

Around 20% of all deliveries are preceded by labour induction, a proportion that has not varied dramatically over recent years. Fetal death was the only indication for labour induction centuries ago, while this is now a very rare indication, with prolonged pregnancy and maternal hypertensive disorders being the major indications for the last 50–60 years. Techniques for inducing labour have also changed from dietary delicacies and verbal threats giving way to physical stimulation mainly achieved by cervical stretching and amniotomy and more recently to sophisticated pharmacological manipulation using oxytocin and prostaglandins, based on our expanding knowledge of the physiological processes involved in spontaneous parturition. Relaxin, antiprogestins, nitric oxide as well as complementary medicines have also been explored in recent years. Successful induction is, however, still not guaranteed and there has been increasing emphasis during the past decade on exploring strategies for identifying the probability of success. Measurement of fetal fibronectin in cervical mucus, maternal serum nitrite/nitrate concentrations, ultrasound delineation of cervical form and electrical impedance measurements across the cervix are all being investigated. Safety, success, and patient satisfaction continue to be the major objectives with economic evaluations now becoming a significant factor in the search for the ideal induction method.

Survival of infants with neural tube defects in the presence of folic acid fortification

OBJECTIVE

Neural tube defects (NTDs) are preventable through preconceptional and periconceptional folic acid intake. Although decreases in the prevalence of NTDs have been reported since folic acid fortification of United States grain products began, it is not known whether folic acid plays a role in reducing the severity of occurring NTDs. Our aim was to determine whether survival among infants born with spina bifida and encephalocele has improved since folic acid fortification and to measure the effects of selected maternal, pregnancy, and birth characteristics on first-year (infant) survival rates.

METHODS

A retrospective cohort study was conducted and included 2841 infants with spina bifida and 638 infants with encephalocele who were born between 1995 and 2001 and were registered in any of 16 participating birth defects monitoring programs in the United States. First-year survival rates for both spina bifida and encephalocele cohorts were measured with Kaplan-Meier estimation; factors associated with improved chances of first-year survival, including birth before or during folic acid fortification, were measured with Cox proportional-hazards regression analysis.

RESULTS

Infants with spina bifida experienced a significantly improved first-year survival rate of 92.1% (adjusted hazard ratio: 0.68; 95% confidence interval: 0.50-0.91) during the period of mandatory folic acid fortification, compared with a 90.3% survival rate for those born before fortification. Infants with encephalocele had a statistically nonsignificant increase in survival rates, ie, 79.1% (adjusted hazard ratio: 0.76; 95% confidence interval: 0.51-1.13) with folic acid fortification, compared with 75.7% for earlier births.

CONCLUSIONS

Folic acid may play a role in reducing the severity of NTDs in addition to preventing the occurrence of NTDs. This phenomenon contributes to our understanding of the efficacy of folic acid. Additionally, as survival of NTD-affected infants improves, health care, education, and family support must expand to meet their needs.