Shoulder dystocia in babies born to Aboriginal mothers with diabetes: a population-based cohort study, 1998-2015.

BACKGROUND: Australian Aboriginal and Torres Strait Islander women with diabetes in pregnancy (DIP) are more likely to have glycaemic levels above the target range, and their babies are thus at higher risk of excessive fetal growth. Shoulder dystocia, defined by failure of spontaneous birth of fetal shoulder after birth of the head requiring obstetric maneuvers, is an obstetric emergency that is strongly associated with DIP and fetal size. The aim of this study was to investigate the epidemiology of shoulder dystocia in Aboriginal babies born to mothers with DIP. METHODS: Stratifying by Aboriginal status, characteristics of births complicated by shoulder dystocia in women with and without DIP were compared and incidence and time-trends of shoulder dystocia were described. Compliance with guidelines aiming at preventing shoulder dystocia in women with DIP were compared. Post-logistic regression estimation was used to calculate the population attributable fractions (PAFs) for shoulder dystocia associated with DIP and to estimate probabilities of shoulder dystocia in babies born to mothers with DIP at birthweights > 3 kg. RESULTS: Rates of shoulder dystocia from vaginal births in Aboriginal babies born to mothers with DIP were double that of their non-Aboriginal counterparts (6.3% vs 3.2%, p < 0.001), with no improvement over time. Aboriginal mothers with diabetes whose pregnancies were complicated by shoulder dystocia were more likely to have a history of shoulder dystocia (13.1% vs 6.3%, p = 0.032). Rates of guideline-recommended elective caesarean section in pregnancies with diabetes and birthweight > 4.5 kg were lower in the Aboriginal women (28.6% vs 43.1%, p = 0.004). PAFs indicated that 13.4% (95% CI: 9.7%-16.9%) of shoulder dystocia cases in Aboriginal (2.7% (95% CI: 2.1%-3.4%) in non-Aboriginal) women were attributable to DIP. Probability of shoulder dystocia among babies born to Aboriginal mothers with DIP was higher at birthweights > 3 kg. CONCLUSIONS: Aboriginal mothers with DIP had a higher risk of shoulder dystocia and a stronger association between birthweight and shoulder dystocia. Many cases were recurrent. These factors should be considered in clinical practice and when counselling women.

A systematic review of the effects of maternal obesity on neonatal outcomes in women with gestational diabetes.

Maternal obesity and gestational diabetes mellitus (GDM) prevalence are increasing, with both conditions associated with adverse neonatal outcomes. This review aimed to determine the risk of adverse outcomes in women with obesity and GDM, compared with women with obesity alone. A systematic search identified 28 eligible articles. Meta-analysis was conducted using a random effects model, to generate pooled estimates (odds ratios, OR, or mean difference, MD). Compared with normal-weight controls, women with obesity had increased risks of large for gestational age (LGA, OR 1.98, 95% CI: 1.56, 2.52) and macrosomia (OR 2.93, 95% CI: 1.71, 5.03); the latter's risk almost double in women with obesity than GDM. Birth weight (MD 113 g, 95% CI: 69, 156) and shoulder dystocia (OR 1.23, 95% CI: 0.85, 1.78) risk was also higher. GDM significantly amplified neonatal risk in women with obesity, with a three- to four-fold risk of LGA (OR 3.22, 95% CI: 2.17, 4.79) and macrosomia (OR 3.71, 95% CI: 2.76, 4.98), as well as higher birth weights (MD 176 g, 95% CI: 89, 263), preterm delivery (OR 1.49, 95% CI: 1.25, 1.77), and shoulder dystocia (OR 1.99, 95% CI: 1.31, 3.03), when compared with normal-weight controls. Our findings demonstrate that maternal obesity increases serious neonatal adverse risk, magnified by the presence of GDM. Effective strategies are needed to safeguard against neonatal complications associated with maternal obesity, regardless of GDM status.

Pitfalls in the diagnostics of shoulder dystocia: an analysis based on the scrutiny of 2274 deliveries.

PURPOSE: Shoulder dystocia is an obstetric emergency with severe complications. Our objective was to evaluate the major pitfalls in the diagnostics of shoulder dystocia, diagnostic descriptions documented in medical records, use of obstetric maneuvers, and their correlations to Erb's and Klumpke's palsy and the use of ICD-10 code 066.0. METHODS: A retrospective, register-based case-control study included all deliveries (n = 181 352) in Hospital District of Helsinki and Uusimaa (HUS) area in 2006-2015. Potential shoulder dystocia cases (n = 1708) were identified from the Finnish Medical Birth Register and the Hospital Discharge Register using ICD-10 codes O66.0, P13.4, P14.0, and P14.1. After thorough assessment of all medical records, 537 shoulder dystocia cases were confirmed. Control group consisted of 566 women without any of these ICD-10 codes. RESULTS: The pitfalls in the diagnostic included suboptimal following of guidelines for making the diagnosis of shoulder dystocia, subjective interpretation of diagnostic criteria, and inexact or inadequate documentation in medical records. The diagnostic descriptions in medical record were highly inconsistent. The use of obstetric maneuvers was suboptimal among shoulder dystocia cases (57.5%). Overall, the use of obstetric maneuvers increased during the study period (from 25.7 to 97.0%, p < 0.001), which was associated with decreasing rate of Erb's palsy and increasing use of ICD-10 code O66.0. CONCLUSION: There are diagnostic pitfalls, which could be addressed by education regarding shoulder dystocia guidelines, by improved use obstetric maneuvers, and more precise documentation. The increased use of obstetric maneuvers was associated with lower rates of Erb's palsy and improved coding of shoulder dystocia.

Shoulder dystocia in deliveries of neonates <3500 grams.

OBJECTIVES: To study risk factors for shoulder dystocia (ShD) among women delivering <3500 g newborn. METHODS: A retrospective case-control study of all term live-singleton deliveries during 2011-2019. Women with neonatal birthweight <3500 g were included. We compared cases of ShD to other deliveries by univariate and multivariable regression. RESULTS: There were 79/41 092 (0.19%) cases of ShD among neonates <3500 g. In multivariable regression analysis, the following factors were independently associated with ShD; operative vaginal delivery (odds ratio [OR] 2.78; 95% confidence interval [CI]: 1.28-6.02, P = 0.009), vaginal birth after cesarean (VBAC, OR 2.74; 1.22-6.13, P = 0.010), sonographic abdominal circumference to biparietal diameter ratio (3.73 among ShD vs. 3.62, OR 1.35; 95% CI: 1.12-1.63, P = 0.001) and sonographic abdominal circumference to head circumference ratio (1.036 among ShD vs. 1.011, OR 3.04; 95% CI: 1.006-9.23, P = 0.049). CONCLUSIONS: There is an association between operative vaginal delivery and ShD also in deliveries <3500 g. Importantly, the proportions between the fetal head and abdominal circumference are a better predictor of ShD than the newborn fetal weight and VBAC is associated with ShD.

Association of Parity and Previous Birth Outcome With Brachial Plexus Birth Injury Risk.

OBJECTIVE: To evaluate the association of maternal delivery history with a brachial plexus birth injury risk in subsequent deliveries and to estimate the effect of subsequent delivery method on brachial plexus birth injury risk. METHODS: We conducted a retrospective cohort study of all live-birth deliveries occurring in California-licensed hospitals from 1996 to 2012. The primary outcome was recurrent brachial plexus birth injury in a subsequent pregnancy. The exposure was delivery history (parity, shoulder dystocia in a previous delivery, or previously delivering a neonate with brachial plexus birth injury). Multiple logistic regression was used to model adjusted associations of delivery history with brachial plexus birth injury in a subsequent pregnancy. The adjusted risk and adjusted risk difference for brachial plexus birth injury between vaginal and cesarean deliveries in subsequent pregnancies were determined, stratified by delivery history, and the number of cesarean deliveries needed to prevent one brachial plexus birth injury was determined. RESULTS: Of 6,286,324 neonates delivered by 4,104,825 individuals, 7,762 (0.12%) were diagnosed with a brachial plexus birth injury. Higher parity was associated with a 5.7% decrease in brachial plexus birth injury risk with each subsequent delivery (adjusted odds ratio [aOR] 0.94, 95% CI 0.92-0.97). Shoulder dystocia or brachial plexus birth injury in a previous delivery was associated with fivefold (0.58% vs 0.11%, aOR 5.39, 95% CI 4.10-7.08) and 17-fold (1.58% vs 0.11%, aOR 17.22, 95% CI 13.31-22.27) increases in brachial plexus birth injury risk, respectively. Among individuals with a history of delivering a neonate with a brachial plexus birth injury, cesarean delivery was associated with a 73.0% decrease in brachial plexus birth injury risk (0.60% vs 2.21%, aOR 0.27, 95% CI 0.13-0.55) compared with an 87.9% decrease in brachial plexus birth injury risk (0.02% vs 0.15%, aOR 0.12, 95% CI 0.10-0.15) in individuals without this history. Among individuals with a history of brachial plexus birth injury, 48.1 cesarean deliveries are needed to prevent one brachial plexus birth injury. CONCLUSIONS: Parity, previous shoulder dystocia, and previously delivering a neonate with brachial plexus birth injury are associated with future brachial plexus birth injury risk. These factors are identifiable prenatally and can inform discussions with pregnant individuals regarding brachial plexus birth injury risk and planned mode of delivery.

Long-term trends in the incidence and management of shoulder dystocia in a tertiary obstetric unit in Hong Kong.

INTRODUCTION: Because there have been changes in the management of macrosomic pregnancies and shoulder dystocia in the past decade, this study was conducted to compare the incidences of shoulder dystocia and perinatal outcomes between the periods of 2000-2009 and 2010-2019. METHODS: This retrospective study was conducted in a tertiary obstetric unit. All cases of shoulder dystocia were identified using the hospital's electronic database. The incidences, maternal and fetal characteristics, obstetric management methods, and perinatal outcomes were compared between the two study periods. RESULTS: The overall incidence of shoulder dystocia decreased from 0.23% (134/58 326) in 2000-2009 to 0.16% (108/65 683) in 2010-2019 (P=0.009), mainly because of the overall decline in the proportion of babies with macrosomia (from 3.3% to 2.3%; P<0.001). The improved success rates of the McRoberts' manoeuvre (from 31.3% to 47.2%; P=0.012) and posterior arm extraction (from 52.9% to 92.3%; P=0.042) allowed a greater proportion of affected babies to be delivered within 2 minutes (from 59.0% to 79.6%; P=0.003). These changes led to a significant reduction in the proportion of fetuses with low Apgar scores: <5 at 1 minute of life (from 13.4% to 5.6%; P=0.042) and <7 at 5 minutes of life (from 11.9% to 4.6%; P=0.045). CONCLUSION: More proactive management of macrosomic pregnancies and enhanced training in the acute management of shoulder dystocia led to significant improvements in shoulder dystocia incidence and perinatal outcomes from 2000-2009 to 2010-2019.

Association between Diabetes in Pregnancy and Shoulder Dystocia by Infant Birth Weight in an Era of Cesarean Delivery for Suspected Macrosomia.

OBJECTIVE: We estimated the association between diabetes and shoulder dystocia by infant birth weight subgroups (<4,000, 4,000-4,500, and >4,500 g) in an era of prophylactic cesarean delivery for suspected macrosomia. STUDY DESIGN: A secondary analysis from the National Institute of Child Health and Human Development U.S. Consortium for Safe Labor of deliveries at ≥24 weeks with a nonanomalous, singleton fetus with vertex presentation undergoing a trial of labor. The exposure was either pregestational or gestational diabetes compared with no diabetes. The primary outcome was shoulder dystocia and secondarily, birth trauma with a shoulder dystocia. We calculated adjusted risk ratios (aRRs) with modified Poison's regression between diabetes and shoulder dystocia and the number needed to treat (NNT) to prevent a shoulder dystocia with cesarean delivery. RESULTS: Among 167,589 assessed deliveries (6% with diabetes), pregnant individuals with diabetes had a higher risk of shoulder dystocia at birth weight <4,000 g (aRR: 1.95; 95% confidence interval [CI]: 1.66-2.31) and 4,000 to 4,500 g (aRR: 1.57; 95% CI: 1.24-1.99), albeit not significantly at birth weight >4,500 g (aRR: 1.26; 95% CI: 0.87-1.82) versus those without diabetes. The risk of birth trauma with shoulder dystocia was higher with diabetes (aRR: 2.29; 95% CI: 1.54-3.45). The NNT to prevent a shoulder dystocia with diabetes was 11 and 6 at ≥4,000 and >4,500 g, versus without diabetes, 17 and 8 at ≥4,000 and >4,500 g, respectively. CONCLUSION: Diabetes increased the risk of shoulder dystocia, even at lower birth weight thresholds than at which cesarean delivery is currently offered. Guidelines providing the option of cesarean delivery for suspected macrosomia may have decreased the risk of shoulder dystocia at higher birth weights. KEY POINTS: · >Diabetes increased the risk of shoulder dystocia, even at lower birth weight thresholds than at which cesarean delivery is currently offered.. · Cesarean delivery for suspected macrosomia may have decreased the risk of shoulder dystocia at higher birth weights.. · These findings can inform delivery planning for providers and pregnant individuals with diabetes..

Incidence trends of shoulder dystocia and associated risk factors: A nationwide analysis in the United States.

OBJECTIVE: To examine recent incidence trends and characteristics of shoulder dystocia. METHODS: This is a retrospective cohort study querying the Healthcare Cost and Utilization Project's National Inpatient Sample. The study population included 9 913 838 vaginal deliveries for national estimates from January 2016 to December 2019. The main outcome measure was the diagnosis of shoulder dystocia. A binary logistic regression model was used to identify characteristics of shoulder dystocia in multivariable analysis. RESULTS: Shoulder dystocia was reported in 228 120 deliveries (23.0 per 1000). The incidence of shoulder dystocia increased from 21.0 to 24.6 per 1000 deliveries during the 4-year study period (17.1% relative increase, P < 0.001). In a multivariable analysis, the recent year of delivery remained an independent factor for shoulder dystocia: adjusted odds ratio (aOR) compared with 2016, 1.09 (95% confidence interval [CI], 1.08-1.11), 1.13 (95% CI, 1.12-1.14), and 1.18 (95% CI, 1.16-1.19) for 2017, 2018, and 2019, respectively. Large for gestational age (aOR 4.33 [95% CI, 4.25-4.40]), diabetes mellitus (pregestational aOR, 4.78 [95% CI, 4.63-4.94], and gestational aOR, 1.69 [95% CI, 1.66-1.71]), and vacuum-assisted delivery (aOR, 2.18 [95% CI, 2.15-2.21]) exhibited the largest risks for shoulder dystocia. CONCLUSION: This national-level analysis identified various risk factors for shoulder dystocia and demonstrated that shouder dystocia cases are increasing gradually in the United States.

Impact of fetal manipulation on maternal and neonatal severe morbidity during shoulder dystocia management.

PURPOSE: There are few data on maternal and neonatal morbidities associated with shoulder dystocia (SD), depending on the use of fetal manipulation (FM). A prior 5-year study was conducted in our center in 2012 for this purpose. Our objective was to compare severe maternal and neonatal morbidities according to FM execution in a larger cohort. METHODS: We conducted a retrospective study between 2007 and 2020. SD was considered when additional maneuvers were required to complete a delivery. Severe maternal morbidity was defined as the occurrence of obstetric anal sphincter injury (OASI). Severe neonatal morbidity was defined as Apgar < 7 at 5 min and/or cord arterial pH < 7.1 and/or or a permanent brachial plexus palsy. We studied these data in the FM group compared to the non- FM group. RESULTS: FM was associated with increased OASI rates (21.1% vs. 3.8%, OR = 6.72 [2.7-15.8]). We found no significant difference in severe neonatal morbidity. Maternal age > 35 and FM appear to be associated with the occurrence of OASI, with ORa = 13.3 [1.5-121.8] and ORa = 5.3 [2.2-12.8], respectively. FM was the only factor associated with the occurrence of severe neonatal morbidity (ORa = 2.3 [1.1-4.8]. The rate of episiotomy was significantly decreased (20% versus 5% p < 0.05) and there was an increase in the rate of SD managed with FM in our center. CONCLUSION: FM is the only factor associated with an increased risk of OASI. In case of failure of non-FM maneuvers, the rapid implementation of FM maneuvers resulted in no difference regarding severe neonatal morbidity.

Impact of simulation training on the management of shoulder dystocia and incidence of permanent brachial plexus birth injury: An observational study.

OBJECTIVE: To study the impact of shoulder dystocia (SD) simulation training on the management of SD and the incidence of permanent brachial plexus birth injury (BPBI). DESIGN: Retrospective observational study. SETTING: Helsinki University Women's Hospital, Finland. SAMPLE: Deliveries with SD. METHODS: Multi-professional, regular and systematic simulation training for obstetric emergencies began in 2015, and SD was one of the main themes. A study was conducted to assess changes in SD management and the incidence of permanent BPBI. The study period was from 2010 to 2019; years 2010-2014 were considered the pre-training period and years 2015-2019 were considered the post-training period. MAIN OUTCOME MEASURES: The primary outcome measure was the incidence of permanent BPBI after the implementation of systematic simulation training. Changes in the management of SD were also analysed. RESULTS: During the study period, 113 085 vertex deliveries were recorded. The incidence of major SD risk factors (gestational diabetes, induction of labour, vacuum extraction) increased and was significantly higher for each of these factors during the post-training period (p < 0.001). The incidence of SD also increased significantly (0.01% vs 0.3%, p < 0.001) during the study period, but the number of children with permanent BPBI decreased by 55% after the implementation of systematic simulation training (0.05% vs 0.02%, p < 0.001). The most significant change in the management of SD was the increased incidence of successful delivery of the posterior arm. CONCLUSIONS: Systematic simulation-based training of midwives and doctors can translate into improved individual and team performance and can significantly reduce the incidence of permanent BPBI.

Increased incidence of shoulder dystocia but a declining incidence of obstetric brachial plexus palsy in vaginally delivered infants.

INTRODUCTION: Obstetric brachial plexus palsy (OBPP) is a serious form of neonatal morbidity. The primary aim of this population-based registry study was to examine temporal trends, 1997-2019, of OBPP in infants delivered vaginally in a cephalic presentation. The secondary aim was to examine temporal changes in the incidence of associated risk factors. MATERIAL AND METHODS: This was a population-based registry study including singleton, cephalic, vaginally delivered infants, 1997-2019, in Sweden. To compare changes in the incidence rates of OBPP and associated risk factors over time, univariate logistic regression was used and odds ratios (OR) with 95% confidence intervals (CI) were calculated. RESULTS: The incidence of OBPP in infants delivered vaginally in a cephalic presentation decreased from 3.1 per 1000 births in 1997 to 1.0 per 1000 births in 2019 (OR 0.31, 95% CI 0.24-0.40). Conversely, the incidence of shoulder dystocia increased from 2.0 per 1000 in 1997 to 3.3 per 1000 in 2019 (OR 1.64, 95% CI 1.34-2.01). Over time, the proportion of women with body mass index of 30 kg/m2 or greater increased (14.5% in 2019 compared with 8.0% in year 1997, OR 1.96, 95% CI 1.89-2.03), more women had induction of labor (20.5% in 2019 compared with 8.6% in 1997, OR 2.74, 95% CI 2.66-2.83) and epidural analgesia (41.2% in 2019 compared with 29.0% in 1997, OR 1.72, 95% CI 1.68-1.75). In contrast, there was a decrease in the rate of operative vaginal delivery (6.0% in 2019, compared with 8.1% in 1997, OR 0.72, 95% CI 0.69, 0.75) and in the proportion of infants with a birthweight greater than 4500 g (2.7% in 2019 compared with 3.8% in 1997, OR 0.70, 95% CI 0.66-0.74). The decline in the incidence of these two risk factors explained only a small fraction of the overall decrease in OBPP between 1997-2002 and 2015-219. CONCLUSIONS: The incidence of OBPP in vaginally delivered infants in a cephalic presentation at birth decreased during the period 1997-2019 despite an increase in important risk factors including shoulder dystocia.

Incidence of obstetric brachial plexus palsy after a training program in shoulder dystocia.

INTRODUCTION: Shoulder dystocia is a nonpreventable obstetric emergency that causes severe complications, such as obstetric brachial plexus palsy. The objective of the study was to determine the incidence of obstetric brachial plexus palsy and other neonatal complications associated with shoulder dystocia in deliveries managed in a university hospital after the implementation of a simulation-based training that was offered to all the labour and delivery staff on a voluntary basis. MATERIAL AND METHODS: Retrospective observational study including all cases of shoulder dystocia and associated complications (mainly obstetric brachial plexus palsy) documented between January 2017 and December 2020, after the implementation of the training. In addition, we collected retrospective data on cases of obstetric brachial plexus palsy that developed in the hospital before the training (2008-2016). RESULTS: In the 2017-2020 period, in the total of 125 cases of shoulder dystocia (amounting to 1.38% of vaginal deliveries), there were 14 cases of obstetric brachial plexus palsy (11.2% of the cases of shoulder dystocia), 7 clavicle fractures and 1 humerus fracture; none of the cases of obstetric brachial plexus palsy was permanent or required treatment or rehabilitation past six months. In the years preceding the training, there were 7 cases of obstetric brachial plexus palsy, 2 permanent and 5 temporary (3 of which required rehabilitation). CONCLUSION: These results reflect the importance of knowing the morbidity present in the labour and delivery ward and the potential benefit of simulation-based training programmes in the resolution of these obstetric complications.

Obstetrics injuries during shoulder dystocia in a tertiary perinatal center.

OBJECTIVES: This study will present our results in management of fetal shoulder dystocia with special consideration of maternal and neonatal outcome. STUDY DESIGN: A retrospective study was performed at a university tertiary perinatal center. The study included data of singleton vaginal term deliveries in the period of 15 years (2006-2020). Analized informations include: obstetrics maternal and neonatal data and outcomes. RESULTS: This period included 45,687 deliveries with diagnosed shoulder dystocia in 254 (0.7 %) cases in vaginal deliveries. Most of the deliveries were spontaneous births 69.7 %, induced deliveries 30.3 %, 47.2 % primiparas and preexisting or gestational diabetes in 21.7 %. The delivery was managed by vacuum extraction in 13.8 %, mediolateral episiotomy in 48.0 % of births, most of the shoulder dystocia were unilateral anterior, while only two cases were diagnosed as more difficult bilateral and 5 cases were recurrent. 87.4 % cases were resolved by McRobert's maneuver, 7.8 % by Barnum's 3.9 % by Wood's maneuver and one case was managed by Menticoglou and by Bourgoise-Siegemundin maneuver. 4.3 % injuries were classified as OASIS of III/IV degree, early postpartum hemorrhage due in 1.6 %. 54.3 % of newborns were male sex, 61.0 % of newborns had birth weight of above 4000 g (mean 4071 g). Maximal Apgar scores were atributed to 92.5 % in first and to 97.2 % in fifth minute, one case that requaired resuscitation. Clavicle fracture was found in 9.5 %, humerus fracture in 0.4 %, transient form of Duchenne Erb obstetrics brachial palsy was diagnosed in only in 7.5 % newborns, while we have not found any case of permanent brachial palsy. CONCLUSIONS: Our results confirmed that strategy of prompt identification of shoulder dystocia accompanied by cessation of axial fetal head traction decrease the risk of brachial plexus strain, injury or tear, while performance of exact obstetrical maneuvers resulted in decanceration of fetal shoulders without permanent obstetrics brachial palsy or cerebral morbidity. We think that our good results corelate with our opinion that the performance of external obstetrical manoeuvres should be done without one minute postpone since efforts should be put in sooner shoulder liberation decreasing the time of fetal hypoxia.

Antenatal risk score for prediction of shoulder dystocia with focus on fetal ultrasound data.

BACKGROUND: Shoulder dystocia is one of the most threatening complications during delivery, and although it is difficult to predict, individual risk should be considered when counseling for mode of delivery. OBJECTIVE: This study aimed to develop and validate a risk score for shoulder dystocia based on fetal ultrasound and maternal data from 15,000 deliveries. STUDY DESIGN: Data were retrospectively obtained of deliveries in 3 tertiary centers between 2014 and 2017 for the derivation cohort and between 2018 and 2020 for the validation cohort. Inclusion criteria were singleton pregnancy, vaginal delivery in cephalic presentation at ≥37+0 weeks' gestation, and fetal biometry data available within 2 weeks of delivery. Independent predictors were determined by multivariate regression analysis in the derivation cohort, and a score was developed on the basis of the effect of the predictors. RESULTS: The derivation cohort consisted of 7396 deliveries with a 0.91% rate of shoulder dystocia, and the validation cohort of 7965 deliveries with a 1.0% rate of shoulder dystocia. Among all women, 13.8% had diabetes mellitus, and 12.1% were obese (body mass index ≥30 kg/m2). Independent risk factors in the derivation cohort were: estimated fetal weight ≥4250 g (odds ratio, 4.27; P=.002), abdominal-head-circumference ≥2.5 cm (odds ratio, 3.96; P<.001), and diabetes mellitus (odds ratio, 2.18; P=.009). On the basis of the strength of effect, a risk score was developed: estimated fetal weight ≥4250 g=2, abdominal-head-circumference ≥2.5 cm=2, and diabetes mellitus=1. The risk score predicted shoulder dystocia with moderate discriminatory ability (area under the receiver-operating characteristic curve, 0.69; P<.001; area under the receiver-operating characteristic curve, 0.71; P<.001) and good calibration (Hosmer-Lemeshow goodness-of-fit; P=.466; P=.167) for the derivation and validation cohorts, respectively. With 1 score point, 16 shoulder dystocia cases occurred in 1764 deliveries, with 0.6% shoulder dystocia incidence and a number needed to treat with cesarean delivery to avoid 1 case of shoulder dystocia of 172 (2 points: 38/1809, 2.1%, 48; 3 points: 18/336, 5.4%, 19; 4 points: 10/96, 10.5%, 10; and 5 points: 5/20, 25%, 4); 40.8% of the shoulder dystocia cases occurred without risk factors. CONCLUSION: The presented risk score for shoulder dystocia may act as a supplemental tool for the clinical decision-making regarding mode of delivery. According to our score model, in pregnancies with a score ≤2, meaning having solely estimated fetal weight ≥4250 g, or abdominal-head-circumference ≥2.5, or diabetes mellitus, cesarean delivery for prevention of shoulder dystocia should not be recommended because of the high number needed to treat to avoid 1 case of shoulder dystocia. Conversely, in patients with a score of ≥4 with or without diabetes mellitus, cesarean delivery may be considered. However, in 40% of the shoulder dystocia cases, no risk factors had been present.

Human shoulder development is adapted to obstetrical constraints.

In humans, obstetrical difficulties arise from the large head and broad shoulders of the neonate relative to the maternal birth canal. Various characteristics of human cranial development, such as the relatively small head of neonates compared with adults and the delayed fusion of the metopic suture, have been suggested to reflect developmental adaptations to obstetrical constraints. On the other hand, it remains unknown whether the shoulders of humans also exhibit developmental features reflecting obstetrical adaptation. Here we address this question by tracking the development of shoulder width from fetal to adult stages in humans, chimpanzees, and Japanese macaques. Compared with nonhuman primates, shoulder development in humans follows a different trajectory, exhibiting reduced growth relative to trunk length before birth and enhanced growth after birth. This indicates that the perinatal developmental characteristics of the shoulders likely evolved to ease obstetrical difficulties such as shoulder dystocia in humans.

Predictors of neonatal brachial plexus palsy subsequent to resolution of shoulder dystocia.

OBJECTIVE: The objective was to ascertain factors among deliveries complicated by shoulder dystocia (SD) and neonatal brachial plexus palsy (NBPP). METHODS: At 11 hospitals, deliveries complicated by SD were identified. The inclusion criteria were vaginal delivery of non-anomalous, singleton at 34-42 weeks. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated. Receiver operating characteristic (ROC) curves were created to evaluate the predictive value of the models for NBPP. RESULTS: Of the 62,939 individuals who delivered vaginally, 1,134 (1.8%) had SD and met other inclusion criteria. Among the analytic cohort, 74 (6.5%) had NBPP. The factor known before delivery which was associated with NBPP was diabetes (aOR = 3.87; 95% CI = 2.13-7.01). After delivery, the three factors associated with NBPP were: (1) birthweight of at least 4000 g (aOR = 1.83; 95% CI = 1.05-3.20); (2) calling for help during the SD (aOR = 4.09, 95% CI = 2.29-7.30), and (3) the duration of SD ≥120 sec (aOR = 2.47, 95% CI = 1.30-4.69). The AUC under the ROC curve for these independent factors was 0.79 (95% CI = 0.77 - 0.82). CONCLUSIONS: Few factors were identified that were associated with NBPP after SD, but they could not reliably predict which neonates will experience the complication.

Accelerated fetal growth velocity across the third trimester is associated with increased shoulder dystocia risk among fetuses who are not large-for-gestational-age: A prospective observational cohort study.

OBJECTIVE: To investigate whether fetuses with accelerated third trimester growth velocity are at increased risk of shoulder dystocia, even when they are not large-for-gestational-age (LGA; estimated fetal weight (EFW) >95th centile). METHODS: Fetal growth velocity and birth outcome data were prospectively collected from 347 nulliparous women. Each had blinded ultrasound biometry performed at 28 and 36 weeks' gestation. Change in EFW and abdominal circumference (AC) centiles between 28-36 weeks were calculated, standardised over exactly eight weeks. We examined the odds of shoulder dystocia with increasing EFW and AC growth velocities among women with 36-week EFW ≤95th centile (non-LGA), who went on to have a vaginal birth. We then examined the relative risk (RR) of shoulder dystocia in cases of accelerated EFW and AC growth velocities (>30 centiles gained). Finally, we compared the predictive performances of accelerated fetal growth velocities to 36-week EFW >95th centile for shoulder dystocia among the cohort planned for vaginal birth. RESULTS: Of the 226 participants who had EFW ≤95th centile at 36-week ultrasound and birthed vaginally, six (2.7%) had shoulder dystocia. For each one centile increase in EFW between 28-36 weeks, the odds of shoulder dystocia increased by 8% (odds ratio (OR [95% Confidence Interval (CI)]) = 1.08 [1.04-1.12], p<0.001). For each one centile increase in AC between 28-36 weeks, the odds of shoulder dystocia increased by 9% (OR[95%CI] = 1.09 [1.05-1.12], p<0.001). When compared to the rest of the cohort with normal growth velocity, accelerated EFW and AC velocities were associated with increased relative risks of shoulder dystocia (RR[95%CI] = 7.3 [1.9-20.6], p = 0.03 and 4.8 [1.7-9.4], p = 0.02 respectively). Accelerated EFW or AC velocities predicted shoulder dystocia with higher sensitivity and positive predictive value than 36-week EFW >95th centile. CONCLUSIONS: Accelerated fetal growth velocities between 28-36 weeks' gestation are associated with increased risk of shoulder dystocia, and may predict shoulder dystocia risk better than the commonly used threshold of 36-week EFW >95th centile.

Antenatal risk prediction of shoulder dystocia: influence of diabetes and obesity: a multicenter study.

PURPOSE: To estimate the risk of shoulder dystocia (SD) in pregnancies with/without maternal diabetes or obesity; to identify antenatal maternal and fetal ultrasound-derived risk factors and calculate their contributions. METHODS: A multicenter retrospective analysis of 13,428 deliveries in three tertiary hospitals (2014-2017) with fetal ultrasound data ≤ 14 days prior to delivery (n = 7396). INCLUSION CRITERIA: singleton pregnancies in women ≥ 18 years old; vertex presentation; vaginal delivery at ≥ 37 weeks of gestation. Estimated fetal weight (EFW) and birth weight (BW) were categorized by steps of 250 g. To evaluate risk factors, a model was performed using ultrasound data with SD as the dependent variable. RESULTS: Diabetes was present in 9.3%; BMI ≥ 30 kg/m2 in 10.4% and excessive weight gain in 39.8%. The total SD rate was 0.9%, with diabetes 2.0% and with obesity 1.9%. These increased with BW 4250-4499 g compared to 4000-4249 g in women with diabetes (12.1% vs 1.9%, P = 0.010) and without (6.1% vs 1.6%, P < 0.001) and at the same BW threshold for women with obesity (9.6% vs 0.6%, P = 0.002) or without (6.4% vs 1.8%, P < 0.001). Rates increased similarly for EFW at 4250 g and for AC-HC at 2.5 cm. Independent risk factors for SD were EFW ≥ 4250 g (OR 3.8, 95% CI 1.5-9.4), AC-HC ≥ 2.5 cm (OR 3.1, 95% CI 1.3-7.5) and diabetes (OR 2.2, 95% CI 1.2-4.0). HC/AC ratio, obesity, excessive weight gain and labor induction were not significant. CONCLUSION: Independent of diabetes, which remains a risk factor for SD, a significant increase may be expected if the EFW is ≥ 4250 g and AC-HC is ≥ 2.5 cm.

The Relationship between Fetal Abdominal Wall Thickness and Intrapartum Complications amongst Mothers with Pregestational Type 2 Diabetes.

OBJECTIVES: To evaluate the utility of fetal abdominal wall thickness (AWT) for predicting intrapartum complications amongst mothers with pregestational type 2 diabetes. METHODS: This was a historical cohort study of pregnant mothers with pregestational type 2 diabetes delivering at a Canadian tertiary-care center between January 1, 2014, and December 31, 2018. Delivery records were reviewed to collect information about demographics and peripartum complications. Stored fetal ultrasound images from 36 weeks' gestation were reviewed to collect fetal biometry and postprocessing measurement of AWT performed in a standardized fashion by 2 blinded and independent observers. The relationship between fetal AWT was then correlated with risk of intrapartum complications including emergency Caesarean section (CS) and shoulder dystocia. RESULTS: 216 pregnant women with type 2 diabetes had planned vaginal deliveries and were eligible for inclusion. Mean maternal age was 31.3 years, and almost all were overweight or obese at the time of delivery (96.8%). Overall, the incidence of shoulder dystocia and emergency intrapartum CS was 7.4% and 17.6%, respectively. There was no difference in mean fetal AWT between those having a spontaneous vaginal delivery (8.2 mm (95% CI 7.9-8.5)) and those needing emergency intrapartum CS (8.1 mm (95% CI 7.4-8.8); p = 0.71) or shoulder dystocia (8.7 mm (95% CI 7.9-9.5); p = 0.23). There was strong interobserver correlation of AWT measurements (r = 0.838; p < 0.00001). The strongest association with intrapartum complications was birthweight (p = 0.003): with birthweight > 4000 grams, the relative risk of shoulder dystocia or CS is 2.75 (95% CI 1.74-4.36; p < 0.001). CONCLUSIONS: There was no obvious benefit of AWT measurement at 36 weeks for predicting shoulder dystocia or intrapartum CS amongst women with type 2 diabetes in our population. The strongest predictor of intrapartum complications remained birthweight, and so studies for improving estimation of fetal weight and evaluating the role of intrapartum ultrasound for predicting risk of delivery complications are still needed.

Evaluation and Management of Fetal Macrosomia.

Macrosomia results from abnormal fetal growth and can lead to serious consequences for the mother and fetus. In cases of suspected macrosomia, patients must be counseled carefully regarding a delivery plan, and Cesarean section should be considered when indicated. Techniques to assess for suspected macrosomia include clinical measurements, ultrasound, and MRI.