Impending macrosomia: will induction of labour modify the risk of caesarean delivery?

Timing of induction of labor in suspected macrosomia: retrospective cohort study, systematic review and meta-analysis

OBJECTIVES

Large-for-gestational age (LGA) is associated with several adverse maternal and neonatal outcomes. Although many studies have found that early induction of labor (IOL) in case of a LGA fetus reduces the incidence of shoulder dystocia, no current guidelines recommend this particular clinical strategy, owing to concerns about increased rates of Cesarean delivery (CD) and neonatal complications. The purpose of this study was to assess whether the timing of IOL in LGA fetuses affected maternal and neonatal outcomes in a single center, and to combine these results with evidence reported in the literature.

METHODS

This study comprised two parts. The first part was a retrospective cohort study that included consecutive patients with a singleton pregnancy and an estimated fetal weight ≥ 90th percentile on ultrasound between 35 + 0 and 39 + 0 weeks' gestation, who were eligible for normal vaginal delivery. The second part of the study was a systematic review of the literature and meta-analysis, including the results of our cohort study as well as those of previous studies that compared IOL with expectant management in patients with a LGA fetus. The perinatal outcomes of the study were CD, operative vaginal delivery, shoulder dystocia, brachial plexus palsy, anal sphincter injury, postpartum hemorrhage, Apgar score, umbilical artery pH, admission to the neonatal intensive care unit, use of continuous positive airway pressure, intracranial hemorrhage, need for phototherapy and bone fracture.

RESULTS

Of the 547 patients included in this retrospective cohort study, 329 (60.1%) underwent IOL and 218 (39.9%) experienced spontaneous labor. Following covariate balancing, the odds of CD were significantly higher in the IOL group compared with the spontaneous-labor group. This difference only became apparent beyond 40 weeks' gestation (hazard ratio, 1.90; P = 0.030). The difference between the IOL and spontaneous-labor groups for the rate of shoulder dystocia was not statistically significant (hazard ratio, 1.57; P = 0.200). Seventeen studies, in addition to our own results, were included in the systematic review and meta-analysis, giving a total population of 111 300 participants. Although there was no significant difference in the rate of CD between IOL and expectant management after pooling the results of included studies, the risk for shoulder dystocia was significantly lower in the IOL group (odds ratio (OR), 0.64 (95% CI, 0.42-0.98); I2 = 19% from 12 studies) when considering only IOL performed before 40 + 0 weeks. When the studies in which IOL was carried out exclusively before 40 + 0 weeks were removed from the analysis, the risk for CD in the remaining studies was significantly higher in the IOL group (OR, 1.46 (95% CI, 1.02-2.09); I2 = 56%). There were no statistically significant differences between the IOL and expectant-management groups for the remaining perinatal outcomes. Nulliparity, history of CD and low Bishop score, but not method of induction, were independent risk factors for intrapartum CD in patients that underwent IOL for LGA.

CONCLUSIONS

The timing of IOL in patients with suspected macrosomia significantly impacts on perinatal adverse outcomes. IOL has no impact on rates of shoulder dystocia but increases the odds of CD when considered irrespective of gestational age; in contrast, IOL may decrease the risk of shoulder dystocia without increasing the risk of other adverse maternal outcomes, in particular CD, when performed before 40 + 0 weeks (GRADE: low/very low). © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Third trimester re-screening for gestational diabetes in morbidly obese women despite earlier negative test can reveal risks for obstetrical complications

AIM

We investigated associations of maternal obesity with late gestational diabetes mellitus (GDM) diagnosis (>34 weeks) in women with previous normal glucose screening, and associations of late GDM with obstetrical outcomes.

METHODS

This retrospective cohort study assessed obstetrical and neonatal outcomes of 238 women with normal (24-28 week) glucose screening results, who underwent late repeat oral glucose tolerance tests (OGTT) (>34 weeks) due to a suspected LGA fetus (54.6%) or polyhydramnios (45.4%). A sub-analysis was performed of outcomes of women with late versus mid-trimester GDM.

RESULTS

The GDM rate in repeat OGTT screening was 22.2% for the total sample, and 33% among women with morbid obesity. Among women with late GDM versus without late GDM, rates were higher for macrosomia, large-for-gestational-age fetus induction of labor, neonatal hypoglycemia, jaundice, and the need for phototherapy. Among women with late GDM, a higher pregestational BMI was associated with adverse maternal and perinatal outcomes. Higher risks for macrosomia and CS due to macrosomia were demonstrated in women with late vs. mid-trimester GDM.

CONCLUSION

Late screening in pregnancy may reveal GDM among women with previous normal glucose screening, particularly among those with late third trimester BMI ≥ 35 kg/m² , GDM in a previous pregnancy or fasting glucose >95 mg/dl. Women diagnosed with GDM at >34 weeks following normal glucose screening at 24-28 weeks are at higher risk for adverse perinatal outcomes. For women with morbid obesity, or suspected macrosomia or polyhydramnios in the late third trimester, and normal glucose screening in the second trimester, retesting should be considered.

Antenatal awareness and obstetric outcomes in large fetuses: A retrospective evaluation

INTRODUCTION

There is currently no consensus on the management of large fetuses in order to minimize fetal complications. The aim of this study was to assess whether antenatal recognition of large-for-gestational age (LGA) reduced poor obstetric newborn outcomes in a hospital where expectant management was used.

MATERIAL AND METHODS

A retrospective cohort study was made of two delivery units at Karolinska University Hospital, Stockholm, Sweden, using expectant management of LGA. All deliveries > 37⁺⁰ weeks of gestation during an 8-year period (2002-2009) were included. The main outcome was severe adverse outcome, a composite variable including neonatal trauma (brachial plexus birth palsy [BPBP] and fractures) and asphyxic sequelae (severe asphyxia, cerebral damage, and fetal/infant death).

RESULTS

The study population consisted of 63,542 appropriate-for-gestational age (AGA) and 3,343 LGA pregnancies (of which 21 % were identified before delivery). Compared to AGA, LGA pregnancies showed a five-fold increased risk of neonatal trauma (OR 5.1, 95 % CI 4.0 - 6.4), but no differences were seen regarding asphyxic sequelae. LGA fetuses identified antenatally had adverse outcomes in 3.7 % of all cases, compared to 3.5 % where LGA was not identified (OR 1.07 95 % CI 0.7 - 1.7). When adjusted for newborn weight deviation, the OR was 0.96, 95 % CI 0.6 - 1.5. There was a three-fold higher risk (OR 3.0, 95 % CI 1.2 - 7.4) of neonatal trauma among non-identified LGA cases > 41⁺⁰ gestational weeks. A total of 81 % of those with LGA were identified after a week 41 routine ultrasound. Out of 68 cases with planned vaginal delivery and expected birth weight > 5000 g, 7.4 % suffered BPBP, representing a 31-fold increase in risk, compared to 0% BPBP among those delivered by elective caesarean section.

CONCLUSION

Antenatal awareness of LGA did not lower the risk of severe adverse outcomes in a unit using expectant management, but those identified postdate were at a lower risk of neonatal trauma. For every 14 fetuses with an expected birth weight > 5000 g delivered by cesarean section, one case of BPBP could be avoided.

Induction of labor versus expectant management among women with macrosomic neonates: a retrospective study

Background: The macrosomic fetus predisposes a variety of adverse maternal and perinatal outcomes. Although older studies have shown no benefit in inducing women of suspected macrosomic fetuses, more updated studies show different information.Objectives: The aim of our study was to compare induction of labor versus expectant management among women with macrosomic neonates weighing more than 4000 g at term (between 37°/7 and 416/7 weeks' gestation).Study design: This was a retrospective cohort study of all live-born singleton pregnancies with macrosomic newborns who were delivered at our institution between 1 January 2000 and 1 June 2015. We compared the outcomes of induction of labor, at each gestational age (GA), between 37 and 41 weeks (study group) with ongoing pregnancy. The primary outcome was cesarean section (CS) rate. Secondary outcomes were composite maternal and neonatal outcome and birth injuries.Results: Overall, out of 3095 patients with macrosomic newborns who were included in the study, 795 women (25.7%) underwent induction of labor. The cesarean section rate was not found to be significantly different between the groups at all gestational ages, nor was the vaginal delivery rate. After adjusting for confounders, induction of labor at 40 and 41 weeks' gestation was associated with composite maternal outcome (adjusted odds ratio (aOR) 1.6, 95% confidence interval (CI): 1.3-2.1; aOR 1.7, 95% CI: 1.3-2.2, respectively) and composite neonatal outcome (aOR 1.6, 95% CI: 1.1-2.4; aOR 1.8, 95% CI: 1.1-2.9). Induction of labor at 40 weeks' gestation was also associated with increased risk of birth injuries (aOR 2.9, 95% CI: 1.4-6).Conclusions: Compared with ongoing pregnancy, induction of labor of women with macrosomic neonates between 37 and 41 weeks of gestation does not reduce the CS rate, nor does it increase the vaginal delivery rate. Moreover, induction of labor of those women beyond 39 weeks' gestation is associated with composite adverse maternal/neonatal outcome, specifically birth injuries.

A systematic scoping review of clinical indications for induction of labour

BACKGROUND

The proportion of women undergoing induction of labour (IOL) has risen in recent decades, with significant variation within countries and between hospitals. The aim of this study was to review research supporting indications for IOL and determine which indications are supported by evidence and where knowledge gaps exist.

METHODS

A systematic scoping review of quantitative studies of common indications for IOL. For each indication, we included systematic reviews/meta-analyses, randomised controlled trials (RCTs), cohort studies and case control studies that compared maternal and neonatal outcomes for different modes or timing of birth. Studies were identified via the databases PubMed, Maternity and Infant Care, CINAHL, EMBASE, and ClinicalTrials.gov from between April 2008 and November 2019, and also from reference lists of included studies. We identified 2554 abstracts and reviewed 300 full text articles. The quality of included studies was assessed using the RoB 2.0, the ROBINS-I and the ROBIN tool.

RESULTS

68 studies were included which related to post-term pregnancy (15), hypertension/pre-eclampsia (15), diabetes (9), prelabour rupture of membranes (5), twin pregnancy (5), suspected fetal compromise (4), maternal elevated body mass index (BMI) (4), intrahepatic cholestasis of pregnancy (3), suspected macrosomia (3), fetal gastroschisis (2), maternal age (2), and maternal cardiac disease (1). Available evidence supports IOL for women with post-term pregnancy, although the evidence is weak regarding the timing (41 versus 42 weeks), and for women with hypertension/preeclampsia in terms of improved maternal outcomes. For women with preterm premature rupture of membranes (24-37 weeks), high-quality evidence supports expectant management rather than IOL/early birth. Evidence is weakly supportive for IOL in women with term rupture of membranes. For all other indications, there were conflicting findings and/or insufficient power to provide definitive evidence.

CONCLUSIONS

While for some indications, IOL is clearly recommended, a number of common indications for IOL do not have strong supporting evidence. Overall, few RCTs have evaluated the various indications for IOL. For conditions where clinical equipoise regarding timing of birth may still exist, such as suspected macrosomia and elevated BMI, researchers and funding agencies should prioritise studies of sufficient power that can provide quality evidence to guide care in these situations.

Induction of labour indications and timing: A systematic analysis of clinical guidelines

BACKGROUND

There is widespread and some unexplained variation in induction of labour rates between hospitals. Some practice variation may stem from variability in clinical guidelines. This review aimed to identify to what extent induction of labour guidelines provide consistent recommendations in relation to reasons for, and timing of, induction of labour and ascertain whether inconsistencies can be explained by variability guideline quality.

METHOD

We conducted a systematic search of national and international English-language guidelines published between 2008 and 2018. General induction of labour guidelines and condition-specific guidelines containing induction of labour recommendations were searched. Guidelines were reviewed and extracted independently by two reviewers. Guideline quality was assessed using the Appraisal of Guidelines for Research and Evaluation II Instrument.

FINDINGS

Forty nine guidelines of varying quality were included. Indications where guidelines had mostly consistent advice included prolonged pregnancy (induction between 41 and 42 weeks), preterm premature rupture of membranes, and term preeclampsia (induction when preeclampsia diagnosed ≥37 weeks). Guidelines were also consistent in agreeing on decreased fetal movements and oligohydramnios as valid indications for induction, although timing recommendations were absent or inconsistent. Common indications where there was little consensus on validity and/or timing of induction included gestational diabetes, fetal macrosomia, elevated maternal body mass index, and twin pregnancy.

CONCLUSION

Substantial variation in clinical practice guidelines for indications for induction exists. As guidelines rated of similar quality presented conflicting recommendations, guideline variability was not explained by guideline quality. Guideline variability may partly account for unexplained variation in induction of labour rates.

Large fetal weight alone in Robson-1 parturients doesn't translate into a risk of Caesarean delivery higher then that of a vaginal birth

OBJECTIVE

The authors analysed the Caesarean section rate as a function of birth weight among Robson-1 parturients and compared with that among the unselected obstetric population.

STUDY DESIGN

A retrospective analysis of birth weight, maternal height and the route of delivery was carried out in an unselected obstetric population of 26,012 parturients. The authors compared birth weight centile distributions of vaginally, and that of abdominally delivered fetuses between Robson-1 parturients as well as those of the total obstetric population.

RESULTS

The 90th birth weight centile of fetuses delivered at 37, 38, 39, 40, 41, and 42 weeks gestation were 3960 g, 3960 g, 4000 g, 3950 g, 4000 g and 3820 g, respectively. Among Robson-1 parturients, 677 fetuses weighed >4000 g, and 448 patients (66%) were delivered vaginally. Maternal height did not influence either the birth-weight-percentiles or the Caesarean-rates substantially. Above the birth weight of 4000 g, the Caesarean-rate among Robson-1 parturient rose similarly to that of the total obstetric population. In the knowledge of the most accurately estimated fetal weight, the odds of Caesarean delivery among Robson-1 parturients was not different from that of the total obstetric population. Among pregnancies with fetuses weighing less than 5000 g, the Caesarean-rate was below 50% in both Robson-1 parturients and the total obstetric population of 10 years.

CONCLUSION

Even the best possible estimation of fetal weight cannot give a valid reason to downplay the intent of vaginal birth based on the fetal size above 3900 g that would be associated with increased odds of Caesarean delivery.

Outcomes of induction of labour in nulliparous women at 38 to 39 weeks pregnancy by clinical indication: An observational study

BACKGROUND

Knowledge of the outcomes of induction of labour for different indications is sparse.

AIMS

To describe the mode of birth and other outcomes for nulliparous women induced at 38-39 weeks gestational age by indication for induction of labour.

MATERIAL AND METHODS

This was a retrospective observational study in a tertiary referral hospital, and a metropolitan teaching hospital in Sydney. The study population was nulliparous women with induction of labour at 38 or 39 completed weeks of pregnancy and a singleton, cephalic presenting baby planning a vaginal birth, from 2009 to 2016. The indication for induction of labour was classified into 12 groups. Mode of birth and other maternal and perinatal outcomes were described in each group, for women who spontaneously laboured at 38 or 39 weeks, and for women who gave birth from 40 completed weeks onward. The main outcome measure was mode of birth.

RESULTS

There were 3330 women with induction of labour at 38 or 39 weeks gestation. Rates of vaginal birth varied widely, ranging from 54% when the indication for induction was suspected large fetus, to 82% when the indication was suspected fetal compromise, and was 74% overall. Indications for caesarean delivery also varied by indication for induction. Among women giving birth ≥40 weeks gestational age, 75% had a vaginal birth.

CONCLUSIONS

In nulliparous women, rates of vaginal birth following induction of labour at 38 or 39 weeks gestation vary widely according to the indication for induction. These data are useful for antenatal counselling.

Childhood health and education outcomes following early term induction for large-for-gestational age: A population-based record linkage study

INTRODUCTION

There is debate about optimal management of pregnancies with a large-for-gestational age baby. A recent randomized controlled trial reported that early term induction of labor reduced cesarean section rates and infant morbidity. However, long term childhood outcomes have not been assessed. The aim of this study was to assess maternal, neonatal and child health and education outcomes for large-for-gestational age babies induced at 37-38 weeks' gestation.

MATERIAL AND METHODS

Population-based record linkage study of term (37+ weeks), cephalic-presenting singleton pregnancies with a large-for-gestational age baby in New South Wales, Australia, 2002-2006. Linked birth, hospital, mortality and education data were used with at least 9 years follow up from birth. Exposure was induction of labor at 37-38 weeks, compared to expectant management (spontaneous birth at ≥37 weeks and planned births at ≥39 weeks). Relative risks and 95% confidence intervals were estimated using Modified Poisson regression with robust variance.

RESULTS

Among 10 174 eligible pregnancies, 412 (4.0%) had an induction at 37-38 weeks. Women in the induction group were less likely to have a cesarean section (RR: 0.65, 95% CI: 0.51-0.82). Infants had higher rates of: low Apgar scores, birth trauma, neonatal jaundice and phototherapy use, and admission to special care nursery or neonatal intensive care than their expectantly managed counterparts. As children, they had higher rates of hospital admission (RR: 1.16, 95% CI: 1.04-1.30) and special needs (RR: 1.98, 95% CI: 1.12-3.50). However, by age 8 there was no difference in overall literacy and numeracy achievement.

CONCLUSIONS

Although women who had an early term labor induction with large-for-gestational age were less likely to have a cesarean section, the increased risk of neonatal morbidities and additional healthcare utilization suggests the need for caution in early induction of large-for-gestational age babies before 39 weeks' gestation.

Is ultrasound measured fetal biometry predictive of intrapartum caesarean section for failure to progress?

BACKGROUND

There are global concerns regarding excessive caesarean rates, which could be reduced by identification of risk factors leading to preventative measures such as induction of labour.

AIMS

This study aims to describe the association between antenatal ultrasound and emergency caesarean section for: (i) failure to progress; (ii) other indications; and (iii) any indication.

MATERIALS AND METHODS

Women who had an ultrasound in pregnancy between 36^(+0/7) to 38^(+6/7) weeks at Royal Prince Alfred Hospital from January 2005 to June 2009 were included. Ultrasound parameters were linked to clinical parameters from the maternity database. Missing clinical data were imputed and multiple logistic regression performed.

RESULTS

Fetal biometry data were available for 2006 pregnancies. After adjusting for maternal age, height, body mass index, parity, previous caesarean section and diabetes, caesarean section for failure to progress was associated with estimated fetal weight (odds ratio (OR) 2.24 (95% CI: 1.76-2.84) per 500 g increase); or biparietal diameter (OR 1.51 (1.16-1.97) per 5 mm increase) and abdominal circumference (OR for the 4th quartile (>75th centile) compared with the 10-25th centile group was 2.09 (1.13-3.85)).* There were also non-linear associations between components of fetal biometry and caesarean section for fetal distress and for any indication.

CONCLUSIONS

Components of fetal biometry in the third trimester are associated with intrapartum caesarean section for failure to progress. These parameters could be incorporated into models to predict emergency caesarean section which could lead to implementation of preventative strategies. *[Corrections added on 29 January 2018, after first online publication, '(OR for the 4th quartile (>7th centile)' has been changed to '(OR for the 4th quartile (>75th centile)'.].

Induction of labor versus expectant management of large-for-gestational-age infants in nulliparous women

Background

There is no apparent consensus on obstetric management, i.e., induction of labor or expectant management of women with suspected large-for-gestational-age (LGA)-fetuses.

Methods and findings

To further examine the subject, a nationwide population-based cohort study from the Swedish Medical Birth Register in nulliparous non-diabetic women with singleton, vertex LGA (>90^th centile) births, 1992–2013, was performed. Delivery of a live-born LGA infant induced at 38 completed weeks of gestation in non-preeclamptic pregnancies, was compared to those of expectant management, with delivery at 39, 40, 41, or 42 completed weeks of gestation and beyond, either by labor induction or via spontaneous labor. Primary outcome was mode of delivery. Secondary outcomes included obstetric anal sphincter injury, 5-minute Apgar<7 and birth injury. Multivariable logistic regression analysis was performed to control for potential confounding. We found that among the 722 women induced at week 38, there was a significantly increased risk of cesarean delivery (aOR = 1.44 95% CI:1.20–1.72), compared to those with expectant management (n = 44 081). There was no significant difference between the groups in regards to risk of instrumental vaginal delivery (aOR = 1.05, 95% CI:0.85–1.30), obstetric anal sphincter injury (aOR = 0.81, 95% CI:0.55–1.19), nor 5-minute Apgar<7 (aOR = 1.06, 95% CI:0.58–1.94) or birth injury (aOR = 0.82, 95% CI:0.49–1.38). Similar comparisons for induction of labor at 39, 40 or 41 weeks compared to expectant management with delivery at a later gestational age, showed increased rates of cesarean delivery for induced women.

Conclusions

In women with LGA infants, induction of labor at 38 weeks gestation is associated with increased risk of cesarean delivery compared to expectant management, with no difference in neonatal morbidity.

Practice Bulletin No. 173: Fetal Macrosomia

Suspected fetal macrosomia is encountered commonly in obstetric practice. As birth weight increases, the likelihood of labor abnormalities, shoulder dystocia, birth trauma, and permanent injury to the neonate increases. The purpose of this document is to quantify those risks, address the accuracy and limitations of methods for estimating fetal weight, and suggest clinical management for a pregnancy with suspected fetal macrosomia.

Pregnancy outcomes in relation to different types of diabetes mellitus and modes of delivery in macrosomic foetuses in Bahrain

Objectives

The mode of delivery in diabetic patients is debatable. This study was designed to assess the pattern of delivery of macrosomic babies with a high prevalence of diabetes mellitus in Bahrain.

Methods

This retrospective analysis was conducted on mothers who delivered babies weighing ≥4.0 Kgs from 2001 to 2011 at Bahrain Defence Force Hospital. Data regarding patients' age, weight, mode of delivery, diabetic status, gestational age and parity were recorded. The main outcome was the effect of diabetes mellitus on the decision to allow vaginal delivery for macrocosmic babies. Other outcomes were failed trial of labour, parity, maternal age and foetal weight on the trial of labour and neonatal morbidity associated with vaginal births.

Results

The incidence of macrosomic babies was 2.2% of total births. Pre-existing diabetes mellitus was 3.9% of the study cohort. The rate of elective Caesarean section increased from 12.5% in non-diabetic mothers to 50% in patients with pre-existing diabetes. In cases of allowing a trial of labour, approximately 70% of patients with pre-existing diabetes had successful vaginal delivery. Patients with a previous delivery were less likely to undergo emergency procedures, but had the same probability for elective Caesarean compared with primigravida. Patient's age and foetal weight had no influence on successful trial of vaginal birth.

Conclusions

There was a trend to offer more elective Caesarean sections in patients with macrosomic babies in the presence of pre-existing diabetes. The majority of patients who were offered a trial of labour achieved vaginal delivery with minimal morbidity.

Induced Labor in Sweden, 1999-2012: A Population-Based Cohort Study

BACKGROUND

Previous studies show contradictory results about the impact of induced labor on the cesarean delivery rate and few studies have investigated the risk of vacuum extraction subsequent to induced labor. The aims of the present study were to describe the rate of induced labor in Sweden from 1999 to 2012, and to assess the risk of unplanned cesarean delivery and vacuum extraction after induced labor in relation to medical complications and length of gestation.

METHODS

A register-based cohort study was conducted, including 1,078,536 women with spontaneous or induced onset of labor who gave birth by noninstrumental vaginal delivery, unplanned cesarean delivery, or vacuum extraction in gestational week 37 + 0 to 41 + 6. Logistic regression was used to study the association between induced labor and instrumental delivery.

RESULTS

The rate of induced labor increased from 7.7 to 12.9 percent among primiparous and from 7.5 to 11.8 percent among multiparous women. Induced labor was associated with 2-3 times greater risk of unplanned cesarean delivery among all women, except multiparas in gestational week 37-38, and with a 20-50 percent higher risk of vacuum extraction after the adjustment for confounding factors. Among women without a recognized medical complication, induced labor was associated with a threefold increased risk of cesarean delivery in gestational week 39-41 and a 40 percent increase in gestational week 37-38 compared with women with spontaneous onset of labor.

CONCLUSIONS

The proportion of induced labors increased substantially during the 14-year study period and was associated with an increased risk of both cesarean delivery and vacuum extraction, even in women without a documented medical complication. The increased risk of instrumental delivery should be taken into account when counseling about the risks and benefits of induced labor.

Timing of induction of labor

Determining the optimal timing for induction of labor is critical in minimizing the risks to maternal and fetal health. While data are available to guide us in some clinical situations, such as hypertension and diabetes, many gaps in knowledge still exist in others, including cholestasis of pregnancy, fetal anomalies, and placental abruption. This review of the currently available literature assesses the risks and benefits of preterm and early term induction in a wide variety of maternal and fetal conditions.

Measures of success: Prediction of successful labor induction

Ideally, all pregnant women would enter labor spontaneously at the safest time to yield the best health outcomes for both themselves and their newborns. Unfortunately, this does not always happen and leaves obstetric providers weighing the maternal and fetal risks of continued expectant management versus labor induction. Several elements have been reported to affect the success rate of an induction, including the Bishop score, maternal parity, body mass index (BMI), age, medical comorbidities, fetal gestational age, and estimated weight, as well as the hospital site and provider practice. Recent data suggest that the decision to induce or continue expectant management in anticipation of labor is an important variable in determining whether a woman has a safe and successful delivery.

Induction of labour versus expectant management for large-for-date fetuses: a randomised controlled trial

BACKGROUND

Macrosomic fetuses are at increased risk of shoulder dystocia. We aimed to compare induction of labour with expectant management for large-for-date fetuses for prevention of shoulder dystocia and other neonatal and maternal morbidity associated with macrosomia.

METHODS

We did this pragmatic, randomised controlled trial between Oct 1, 2002, and Jan 1, 2009, in 19 tertiary-care centres in France, Switzerland, and Belgium. Women with singleton fetuses whose estimated weight exceeded the 95th percentile, were randomly assigned (1:1), via computer-generated permuted-block randomisation (block size of four to eight) to receive induction of labour within 3 days between 37(+0) weeks and 38(+6) weeks of gestation, or expectant management. Randomisation was stratified by centre. Participants and caregivers were not masked to group assignment. Our primary outcome was a composite of clinically significant shoulder dystocia, fracture of the clavicle, brachial plexus injury, intracranial haemorrhage, or death. We did analyses by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00190320.

FINDINGS

We randomly assigned 409 women to the induction group and 413 women to the expectant management group, of whom 407 women and 411 women, respectively, were included in the final analysis. Mean birthweight was 3831 g (SD 324) in the induction group and 4118 g (392) in the expectant group. Induction of labour significantly reduced the risk of shoulder dystocia or associated morbidity (n=8) compared with expectant management (n=25; relative risk [RR] 0·32, 95% CI 0·15-0·71; p=0·004). We recorded no brachial plexus injuries, intracranial haemorrhages, or perinatal deaths. The likelihood of spontaneous vaginal delivery was higher in women in the induction group than in those in the expectant management group (RR 1·14, 95% CI 1·01-1·29). Caesarean delivery and neonatal morbidity did not differ significantly between the groups.

INTERPRETATION

Induction of labour for suspected large-for-date fetuses is associated with a reduced risk of shoulder dystocia and associated morbidity compared with expectant management. Induction of labour does not increase the risk of caesarean delivery and improves the likelihood of spontaneous vaginal delivery. These benefits should be balanced with the effects of early-term induction of labour.

FUNDING

Assistance Publique-Hôpitaux de Paris and the University of Geneva.

Gestational diabetes mellitus and macrosomia: a literature review

BACKGROUND

Fetal macrosomia, defined as a birth weight ≥ 4,000 g, may affect 12% of newborns of normal women and 15-45% of newborns of women with gestational diabetes mellitus (GDM). The increased risk of macrosomia in GDM is mainly due to the increased insulin resistance of the mother. In GDM, a higher amount of blood glucose passes through the placenta into the fetal circulation. As a result, extra glucose in the fetus is stored as body fat causing macrosomia, which is also called 'large for gestational age'. This paper reviews studies that explored the impact of GDM and fetal macrosomia as well as macrosomia-related complications on birth outcomes and offers an evaluation of maternal and fetal health.

SUMMARY

Fetal macrosomia is a common adverse infant outcome of GDM if unrecognized and untreated in time. For the infant, macrosomia increases the risk of shoulder dystocia, clavicle fractures and brachial plexus injury and increases the rate of admissions to the neonatal intensive care unit. For the mother, the risks associated with macrosomia are cesarean delivery, postpartum hemorrhage and vaginal lacerations. Infants of women with GDM are at an increased risk of becoming overweight or obese at a young age (during adolescence) and are more likely to develop type II diabetes later in life. Besides, the findings of several studies that epigenetic alterations of different genes of the fetus of a GDM mother in utero could result in the transgenerational transmission of GDM and type II diabetes are of concern.

Perinatal outcomes following an earlier post-term labour induction policy: a historical cohort study

OBJECTIVE

To assess the changes in perinatal outcomes in children born from 37 weeks of gestation after implementation of a more proactive labour induction practice from 2009.

DESIGN

Register-based cohort study.

SETTING

Denmark, 2000-12.

POPULATION

Newborns from 37 weeks of gestation.

METHODS

Perinatal outcomes were estimated using a logistic regression analysis with adjustment for gestational age, maternal age, parity, plurality, smoking and body mass index.

MAIN OUTCOME MEASURES

Perinatal outcomes.

RESULTS

A total of 770 926 infants were included. Labour induction from 37 weeks increased from 9.7% in 2000-02 to 22.5% in 2011-12. From 2003-05 to 2011-12, the risk of umbilical cord pH < 7.0 decreased by 23%; odds ratio (OR) 0.77 (95% confidence interval 0.67-0.89), and the adjusted OR of Apgar score < 7 at 5 minutes was unchanged. The risk of admission to neonatal intensive care units increased by 56%; OR 1.56 (1.47-1.66), whereas the risk of neonatal deaths decreased by 44%; OR 0.56 (0.45-0.70). The risk of cerebral palsy was from 2000-02 to 2009-10 reduced by 26%; OR 0.74 (0.60-0.90). The proportion of infants born with fetal weight ≥ 4500 g decreased by one-third; OR 0.68 (0.65-0.71). However, the risk of shoulder dystocia increased by 32%; OR 1.32 (1.21-1.44), whereas the risk of peripheral nerve injuries was reduced by 43%; OR 0.57 (0.45-0.73).

CONCLUSION

The results suggest an overall improvement in perinatal outcomes as a result of a more proactive post-term labour induction practice.

Diabetes in pregnancy: timing and mode of delivery

Diabetes in pregnancy represents a risk condition for adverse maternal and feto-neonatal outcomes and many of these complications might occur during labor and delivery. In this context, the obstetrician managing women with pre-existing and gestational diabetes should consider (1) how these conditions might affect labor and delivery outcomes; (2) what are the current recommendations on management; and (3) which other factors should be considered to decide about the timing and mode of delivery. The analysis of the studies considered in this review leads to the conclusion that the decision to deliver should be primarily intended to reduce the risk of stillbirth, macrosomia, and shoulder dystocia. In this context, this review provides useful information for managing specific subgroups of diabetic women that may present overlapping risk factors, such as women with insulin-requiring diabetes and/or obesity and/or prenatal suspicion of macrosomic fetus. To date, the lack of definitive evidences and the complexity of the problem suggest that the "appropriate" clinical management should be customized according with the clinical condition, the type and mode of intervention, its consequences on outcomes, and considering the woman's consent and informed decisions.

Does induction of labor for constitutionally large-for-gestational-age fetuses identified in utero reduce maternal morbidity?

BACKGROUND

The number of infants with a birth weight > 97th percentile for gestational age has increased over the years. Although some studies have examined the interest of inducing labor for fetuses with macrosomia suspected in utero, only a few have analyzed this suspected macrosomia according to estimated weight at each gestational age. Most studies have focused principally on neonatal rather than on maternal (and still less on perineal) outcomes. The principal aim of this study was to assess whether a policy of induction of labor for women with a constitutionally large-for-gestational-age fetus might reduce the occurrence of severe perineal tears; the secondary aims of this work were to assess whether this policy would reduce either recourse to cesarean delivery during labor or neonatal complications.

METHODS

This historical cohort study (n = 3077) analyzed records from a French perinatal database. Women without diabetes and with a cephalic singleton term pregnancy were eligible for the study. We excluded medically indicated terminations of pregnancy and in utero fetal deaths. Among the pregnancies with fetuses suspected, before birth, of being large-for-gestational-age, we compared those for whom labor was induced from ≥ 37 weeks to ≤ 38 weeks+ 6 days (n = 199) to those with expectant obstetrical management (n = 2878). In this intention-to-treat analysis, results were expressed as crude and adjusted relative risks.

RESULTS

The mean birth weight was 4012 g ± 421 g. The rate of perineal lesions did not differ between the two groups in either primiparas (aRR: 1.06; 95% CI: 0.86-1.31) or multiparas (aRR: 0.94; 95% CI: 0.84-1.05). Similarly, neither the cesarean rate (aRR: 1.11; 95% CI: 0.82-1.50) nor the risks of resuscitation in the delivery room or of death in the delivery room or in the immediate postpartum or of neonatal transfer to the NICU (aRR = 0.94; 95% CI: 0.59-1.50) differed between the two groups.

CONCLUSIONS

A policy of induction of labor for women with a constitutionally large-for-gestational-age fetus among women without diabetes does not reduce maternal morbidity.

Timing of delivery in women with diabetes in pregnancy

The incidence of both gestational and pre-gestational diabetes is increasing worldwide. The main cause of this increase is likely the concomitant increase in the incidence of global obesity, but in the case of gestational diabetes, changes in the diagnostic criteria are also a contributing factor. The adverse outcomes associated with pre-gestational diabetes are well known and have led clinicians to implement various strategies that include increased fetal surveillance and induction of labour at various gestational ages. In many cases these same strategies have been applied in clinical practice also to women with gestational diabetes despite there being differences in the type and magnitude of perinatal complications associated with this diagnosis. Despite the widespread application of these clinical practices, there is a paucity of quality data in the medical literature to guide the clinician in choosing a strategy for fetal surveillance and timing of delivery in both gestational diabetes and pre-gestational diabetes pregnancies. In the following review, we will discuss the rationale and consequences of planned delivery in gestational diabetes and pre-gestational diabetes, the evidence supporting different strategies for delivery and finally highlight future targets for research in this area.

The risk factors for failure of labor induction: a cohort study

PURPOSE

To assess how some factors may influence the failure of labor induction.

METHODS

We conducted a prospective observational study from January 2009 to December 2011 with 248 patients who were admitted to the Obstetrics Unit of Ferrara University for labor induction. We selected only patients with unfavorable characteristics such as nulliparity, maternal and gestational age, and Bishop score and specific obstetric conditions such as mild preeclampsia, isolated oligohydramnios, premature rupture membrane, gestational diabetes, and hypertension for the success of labor induction.

RESULTS

The induction was carried out by rapid-release gel dinoprostone. 200 patients (80.6 %) delivered vaginally (Group A), while 48 (19.4 %) underwent a cesarean section (Group B). Maternal age was one independent significant variable (p = 0.01, OR 1.08) determining the risk of cesarean delivery. Patients affected by mild preeclampsia had a three times higher risk for cesarean section. Despite the several unfavorable characteristics of the patients, the cesarean section rate was comparable to that of the normal population.

CONCLUSIONS

Several factors and clinical conditions historically considered as negative predictors of induction result should be reassessed. The success of labor induction is determined by many maternal and fetal variables, which must all be taken into account to avoid unnecessary cesarean sections.

Fetal and maternal outcomes in pregnancies complicated with fetal macrosomia

BACKGROUND

Fetal macrosomia remains a considerable challenge in current obstetrics due to the fetal and maternal complications associated with this condition.

AIM

This study was designed to determine the prevalence of fetal macrosomia and associated fetal and maternal morbidity and mortality in the Al Qassim Region of Saudi Arabia.

MATERIALS AND METHODS

This register-based study was conducted from January 1, 2011 through December 30, 2011 at the Maternity and Child Hospital, Qassim, Saudi Arabia. Macrosomia was defined as birth weight of 4 kg or greater. Malformed babies and those born dead were excluded.

RESULTS

The total number of babies delivered was 9241; of these, 418 were macrosomic. Thus, the prevalence of fetal macrosomia was 4.5%. The most common maternal complications were postpartum hemorrhage (5 cases, 1.2%), perineal tear (7 cases, 1.7%), cervical lacerations (3 cases, 0.7%), and shoulder dystocia (40 cases, 9.6%) that resulted in 4 cases of Erb's palsy (0.96%), and 6 cases of bone fractures (1.4%). The rate of cesarean section among women delivering macrosomic babies was 47.6% (199), while 52.4% (219) delivered vaginally.

CONCLUSION

Despite extensive efforts to reduce fetal and maternal complications associated with macrosomia, considerable fetal and maternal morbidity remain associated with this condition.