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.

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.

Shoulder dystocia by severity in families: A nationwide population study.

INTRODUCTION: Previous studies have established a history of shoulder dystocia as an important risk factor for shoulder dystocia, but studies on shoulder dystocia by severity are scarce. It is unknown if shoulder dystocia tends to be passed on between generations. We aimed to assess the recurrence risk of shoulder dystocia by severity in the same woman and between generations on both the maternal and paternal side. We also assessed the likelihood of a second delivery and planned cesarean section after shoulder dystocia. MATERIAL AND METHODS: This was a population-based cohort study, using data from the Medical Birth Registry of Norway. To study recurrence in the same mother, we identified 1 091 067 pairs of first and second, second and third, and third and fourth births in the same mother. To study intergenerational recurrence, we identified an individual both as a newborn and as a mother or father in 824 323 mother-offspring pairs and 614 663 father-offspring pairs. We used Bayesian log-binomial multilevel regression to calculate relative risks (RR) with 95% credible intervals. RESULTS: In subsequent deliveries in the same woman the unadjusted RR of recurrence was 7.05 (95% credible interval 6.39-7.79) and 2.99 (2.71-3.31) after adjusting for possible confounders, including current birthweight. The RRs were higher with severe shoulder dystocia as exposure or outcome. With severe shoulder dystocia as both exposure and outcome, unadjusted and adjusted RR was 20.42 (14.25-29.26) and 6.29 (4.41-8.99), respectively. Women with severe and mild shoulder dystocia and those without had subsequent delivery rates of 71.1, 68.9 and 69.0%, respectively. However, the rates of planned cesarean section in subsequent deliveries for those without shoulder dystocia, mild and severe were 1.3, 5.2 and 16.0%, respectively. On the maternal side the unadjusted inter-generational RR of recurrence was 2.82 (2.25-3.54) and 1.41 (1.05-1.90) on the paternal side. Corresponding adjusted RRs were 1.90 (1.51-2.40) and 1.19 (0.88-1.61), respectively. CONCLUSIONS: We found a strong recurrence risk of shoulder dystocia, especially severe, in subsequent deliveries in the same woman. The inter-generational recurrence risk was higher on the maternal than paternal side. Women with a history of shoulder dystocia had more often planned cesarean section.

Maternal and neonatal complications of shoulder dystocia with a focus on obstetric maneuvers: A case-control study of 1103 deliveries.

INTRODUCTION: Shoulder dystocia is a severe obstetric emergency that can cause substantial neonatal and maternal complications. This study aims to assess the performed obstetric maneuvers and their frequency, success, and association with maternal and neonatal complication rates. MATERIAL AND METHODS: The study population was collected among all deliveries in the Hospital District of Helsinki and Uusimaa between 2006 and 2015 (n = 181 352) by searching for ICD-10 codes for shoulder dystocia, brachial plexus injury and clavicle fracture. Shoulder dystocia cases (n = 537) were identified by reviewing the medical records. Shoulder dystocia cases treated with one or two maneuvers were compared with those treated with at least three. Medical records of a matched control group constituting of 566 parturients without any of the forementioned ICD-10 codes were also scrutinized. RESULTS: Using the four most common obstetric maneuvers (McRoberts maneuver, suprapubic pressure, rotational maneuvers, the delivery of the posterior arm) significantly increased during the study period with individual success rates of 61.0%, 71.9%, 68.1% and 84.8%, respectively. Concurrently, the rate of brachial plexus injury and combined neonatal morbidity significantly declined from 50% to 24.2% (p = 0.02) and from 91.4% to 48.5% (p < 0.001). Approximately 75% of shoulder dystocia cases treated with maneuvers were resolved by the McRoberts maneuver and/or suprapubic pressure, but each of the four most performed maneuvers significantly increased the cumulative success rate individually and statistically (p < 0.001). The rates of brachial plexus injury and combined neonatal morbidity were at their highest (52.9% and 97.8%) when none of the maneuvers were performed and at their lowest when two maneuvers were performed (43.0% and 65.4%). The increasing number (≥3) of maneuvers did not affect the combined maternal or neonatal morbidity or brachial plexus injury but increased the risk for third- or fourth-degree lacerations (odds ratio 2.91, 95% confidence interval 1.17 to 7.24). CONCLUSIONS: The increased use of obstetric maneuvers during the study period was associated with decreasing rates of neonatal complications; conversely, the lack of obstetric maneuvers was associated with the highest rate of neonatal complications. These emphasize the importance of education, maneuver training and urgently performing shoulder dystocia maneuvers according to the international protocol guidelines.

Incidence of shoulder dystocia and risk factors for recurrence in the subsequent pregnancy-A historical register-based cohort study.

INTRODUCTION: Shoulder dystocia is a rare obstetric complication, and the risk of recurrence is important for planning future deliveries. MATERIAL AND METHODS: The objectives of our study were to estimate the incidence and risk factors for recurrence of shoulder dystocia and to identify women at high risk of recurrence in a subsequent vaginal delivery. The study design was a nationwide register-based study including data from the Danish Medical Birth Registry and National Patient Register in the period 2007-2017. Nulliparous women with a singleton fetus in cephalic presentation were included for analysis of risk factors in index and subsequent delivery. RESULTS: During the study period, 6002 cases of shoulder dystocia were reported with an overall incidence among women with vaginal delivery of 1.2%. Among 222 225 nulliparous women with vaginal births, shoulder dystocia complicated 2209 (1.0%) deliveries. A subsequent birth was registered in 1106 (50.1%) of the women with shoulder dystocia in index delivery of which 837 (77.8%) delivered vaginally. Recurrence of shoulder dystocia was reported in 60 (7.2%) with a six-fold increased risk compared with women without a prior history of shoulder dystocia (risk ratio [RR] 5.70, 95% confidence interval [CI]: 4.41 to 7.38; adjusted RR 3.06, 95% CI: 2.03 to 4.68). Low maternal height was a significant risk factor for recurrence of shoulder dystocia. In the subsequent delivery, significant risk factors for recurrence were birthweight >4000 g, positive fetal weight difference exceeding 250 g from index to subsequent delivery, stimulation with oxytocin and operative vaginal delivery. In the subsequent pregnancy following shoulder dystocia, women who underwent a planned cesarean (n = 176) were characterized by more advanced age and a higher prevalence of diabetes in the subsequent pregnancy. Furthermore, they had more often experienced operative vaginal delivery, severe perineal lacerations, and severe neonatal complications at the index delivery. CONCLUSIONS: The incidence of shoulder dystocia among nulliparous women with vaginal delivery was 1.0% with a 7.2% risk of recurrence in a population where about 50% had a subsequent birth and of these 78% had subsequent vaginal delivery. Important risk factors for recurrence were low maternal height, increase of birthweight ≥250 g from index to subsequent delivery and operative vaginal delivery.

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.

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.

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.

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..

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.

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.

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.

Detemir vs neutral protamine Hagedorn insulin for diabetes mellitus in pregnancy: a comparative effectiveness, randomized controlled trial.

BACKGROUND: Insulin detemir, being used increasingly during pregnancy, may have pharmacologic benefits compared with neutral protamine Hagedorn. OBJECTIVE: We evaluated the probability that compared with treatment with neutral protamine Hagedorn, treatment with insulin detemir reduces the risk for adverse neonatal outcome among individuals with type 2 or overt type 2 diabetes mellitus (gestational diabetes mellitus diagnosed at <20 weeks' gestation). STUDY DESIGN: We performed a multiclinic randomized controlled trial (September 2018 to January 2020), which included women with singleton gestation with type 2 or overt type 2 diabetes mellitus who sought obstetrical care at ≤21 weeks' gestation. Participants were randomized to receive either insulin detemir or neutral protamine Hagedorn by a clinic-stratified scheme. The primary outcome was a composite of adverse neonatal outcomes, including shoulder dystocia, large for gestational age, neonatal intensive care unit admission, respiratory distress (defined as the need of at least 4 hours of respiratory support with supplemental oxygen, continuous positive airway pressure or ventilation at the first 24 hours of life), or hypoglycemia. The secondary neonatal outcomes included gestational age at delivery, small for gestational age, 5-minute Apgar score of <7, lowest glucose level, need for intravenous glucose, respiratory distress syndrome, need for mechanical ventilation or continuous positive airway pressure, neonatal jaundice requiring therapy, brachial plexus injury, and hospital length of stay. The secondary maternal outcomes included hypoglycemic events, hospital admission for glucose control, hypertensive disorder of pregnancy, maternal weight gain, cesarean delivery, and postpartum complications. We used the Bayesian statistics to estimate a sample size of 108 to have >75% probability of any reduction in the primary outcome, assuming 80% power and a hypothesized effect of 33% reduction with insulin detemir. All analyses were intent to treat under a Bayesian framework with neutral priors (a priori assumed a 50:50 likelihood of either intervention being better; National Clinical Trial identifier 03620890). RESULTS: There were 108 women randomized in this trial (57 in insulin detemir and 51 in neutral protamine Hagedorn), and 103 women were available for analysis of the primary outcome (n=5 for pregnancy loss before 24 weeks' gestation). Bayesian analysis indicated an 87% posterior probability of reduced primary outcome with insulin detemir compared with neutral protamine Hagedorn (posterior adjusted relative risk, 0.88; 95% credible interval, 0.61-1.12). Bayesian analyses for secondary outcomes showed consistent findings of lower adverse maternal outcomes with the use of insulin detemir vs neutral protamine Hagedorn: for example, maternal hypoglycemic events (97% probability of benefit; posterior adjusted relative risk, 0.59; 95% credible interval, 0.29-1.08) and hypertensive disorders (88% probability of benefit; posterior adjusted relative risk, 0.81; 95% credible interval, 0.54-1.16). CONCLUSION: In our comparative effectiveness trial involving individuals with type 2 or overt type 2 diabetes mellitus, use of insulin detemir resulted in lower rates of adverse neonatal and maternal outcomes compared with neutral protamine Hagedorn.

Rising trends in the incidence of shoulder dystocia and development of a novel shoulder dystocia risk score tool: a nationwide population-based study of 800 484 Finnish deliveries.

INTRODUCTION: Shoulder dystocia has remained an unpredictable and feared emergency in obstetrics. Some risk factors have been identified but nevertheless there is a lack of risk evaluation tools in clinical practice. The aim of this study was to evaluate the incidence and risk factors of shoulder dystocia in the Finnish population and to develop a shoulder dystocia risk score tool. MATERIAL AND METHODS: This retrospective, population-based study included all deliveries in Finland between 2004 and 2017 (n = 800 484). The annual numbers of shoulder dystocia diagnoses were gathered from nationwide Finnish Medical Birth Register and Hospital Discharge Register. The incidence of shoulder dystocia was calculated in subgroups according to the mode of delivery, maternal diabetes status, body mass index (BMI), age, parity and gestational age. Based on these numbers, a shoulder dystocia risk score tool was created. RESULTS: The overall incidence of shoulder dystocia was 0.18%. It increased significantly during the study period from 0.10% to 0.32% (P < .001). More specifically, the incidence increased significantly in all analyzed subgroups except for women with BMI <18.5 or age <20 years. To evaluate the importance of risk factors, practical and simple shoulder dystocia risk score tool was created. Instrumental vaginal delivery, maternal diabetes of any kind, BMI ≥25, age ≥40 years and gestational age ≥41 weeks were associated with higher shoulder dystocia risk compared with non-diabetic, non-obese and younger women with spontaneous deliveries before 41 weeks of gestation. In our risk score tool, cases with shoulder dystocia had a significantly higher number of risk points than those without it (15.2 vs 10.4, P < .001). The risk was significantly high when the scores were ≥18 points (relative risk 9.54, 95% confidence interval 8.61-10.57). CONCLUSIONS: The incidence of shoulder dystocia in Finland increased during the study period but it is still low compared with previous studies from other countries. In clinical daily practice, the new shoulder dystocia risk score tool helps to evaluate the individual risk profile of the parturient. According to this risk score tool, the highest risk was found with the combination of instrumental vaginal delivery, maternal diabetes, BMI ≥25, age ≥40 years and gestational age ≥41 weeks.

How common is substandard obstetric care in adverse events of birth asphyxia, shoulder dystocia and postpartum hemorrhage? Findings from an external inspection of Norwegian maternity units.

INTRODUCTION: The Norwegian Board of Health Supervision inspects healthcare institutions to ensure safety and quality of health and welfare services. A planned inspection of 12 maternity units aimed to investigate the practice of obstetric care in the case of birth asphyxia, shoulder dystocia and severe postpartum hemorrhage. MATERIAL AND METHODS: The inspection was carried out at two large, four medium and six small maternity units in Norway in 2016 to investigate adverse events that occurred between 1 January and 31 December 2014. Six of them were selected as control units. The Norwegian Board of Health Supervision searched the Medical Birth Registry of Norway to identify adverse events in each of the categories and then requested access to the medical records for all patients identified. Information about guidelines, formal teaching and simulation training at each unit was obtained by sending a questionnaire to the obstetrician in charge of each maternity unit. RESULTS: The obstetric units inspected had 553 serious adverse events of birth asphyxia, shoulder dystocia or severe postpartum hemorrhage among 17 323 deliveries. Twenty-nine events were excluded from further analysis due to erroneous coding or missing data in the patients' medical records. We included 524 cases (3.0% of all deliveries) of adverse events in the final analysis. Medical errors caused by substandard care were present in 295 (56.2%) cases. There was no difference in the prevalence of substandard care among the maternity units according to their size. Surprisingly, we found significantly fewer cases with substandard care in the units which the supervisory authorities considered particularly risky before the inspection, compared with the control units. Seven of the 12 units had regular formal teaching and training arrangements for obstetric healthcare personnel as outlined in the national guidelines. CONCLUSIONS: Prevalence of adverse events was 3% and similar in all maternity units irrespective of their size. A breach in the standard of care was observed in 56.2% of cases and almost half of the maternity units did not follow national recommendations regarding teaching and practical training of obstetric personnel, suggesting that they should focus on implementing guidelines and training their staff.

Shoulder Dystocia during Delivery and Long-Term Neurological Morbidity of the Offspring.

OBJECTIVE: The study aimed to evaluate risk factors and implications of shoulder dystocia (SD) on the neurological outcome of successfully delivered offspring. STUDY DESIGN: This is a cohort analysis including 207,571 deliveries. Risk factors for SD were evaluated using general estimation equation multivariable analyses. Offspring hospitalization incidence up to age 18 years due to neurological conditions was compared between both groups. Kaplan-Meyer curve was used to assess the cumulative hospitalization incidence. Cox proportional hazards model was used to control for confounders. RESULTS: SD complicated 0.2% (n = 353) of deliveries included in the study (n = 207,571). Risk factors for SD were fetal macrosomia, maternal diabetes mellitus, male gender, and advanced maternal age (p < 0.05 for all). Higher perinatal mortality was observed among SD cases (2.8 vs. 0.4%, p < 0.001). In most of the investigated neurological conditions no significant differences were found between the groups. Comparable rates of cumulative neurological-related hospitalization were observed (log rank p-value = 0.342) as well as lack of association between SD and neurological hospitalization (adjusted HR = 0.73; 95% CI 0.36-1.47; p = 0.381) when controlled for gestational age. CONCLUSION: Risk factors for SD are macrosomia, diabetes mellitus, male gender, and advanced maternal age. SD is not associated with long-term neurological morbidity of the offspring.

The association of vacuum-assisted delivery and shoulder dystocia among macrosomic newborns: a retrospective study.

PURPOSE: Although shoulder dystocia (ShD) is associated with fetal macrosomia and vacuum-assisted delivery (VAD), the independent role of the latter in the occurrence of ShD is yet to be completely elucidated, as it is difficult to study its true independent contribution to ShD formation in the presence of many confounding factors. Therefore, we aimed to study whether VAD is independently associated with an increased risk for ShD among macrosomic newborns. METHODS: A retrospective cohort study from a single tertiary medical center including all women who delivered vaginally a macrosomic infant during 2011-2020. We allocated the study cohort into two groups: (1) VAD (2) spontaneous vaginal deliverys, and analyzed risk factors for ShD. A multivariate regression analysis was performed to identify determinants independently associated with ShD occurrence. RESULTS: Of 2,664 deliveries who met the study inclusion criteria, 118 (4.4%) were VAD. The rate of ShD in the entire cohort was 108/2664 (4.1%). The following factors were more frequent among the VAD group: no previous vaginal delivery [odds ratio (OR) 2.4 (95% confidence interval (CI) 1.4-4.0, p < 0.001)], prolonged second stage (OR 11.9; 95% CI 8.1-17.6, p < 0.01), induction of labor (OR 2.4; 95% CI 1.5-3.8, p < 0.01) and ShD (OR 2.0; 95% CI 1.0-4.1, p = 0.04). ShD was associated with higher rates of maternal height < 160 cm (OR 2.0; 95% CI 1.3-3.1, p < 0.01), pregestational diabetes (OR 7.2; 95% CI 2.0-26.8, p = 0.01), hypertensive disorder (OR 2.6; 95% CI 1.1-6.2, p = 0.02) and higher birthweight (mean 4,124 vs. 4,167 g, p < 0.01). On multivariate regression analysis, the following factors remained independently associated with ShD occurrence: increased birthweight (aOR 1.0; 95% CI 1.0-1.0, p < 0.01), pregestational diabetes (aOR 5.3; 95% CI 1.1-25.0, p = 0.03), while maternal height was negatively associated with ShD (aOR 0.9; 95% CI 0.9-0.9, p < 0.01). CONCLUSION: In deliveries of neonates above 4000 g, VAD did not independently increase the risk of ShD occurrence. Therefore, when expeditious delivery of a macrosomic infant is required, VAD is a viable option.

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.

Undiagnosed type 2 diabetes during pregnancy is associated with increased perinatal mortality: a large population-based cohort study in Ontario, Canada.

AIM: To compare perinatal outcomes in women with undiagnosed diabetes with gestational diabetes alone, pre-existing diabetes and women without diabetes, and to identify risk factors which distinguish them from women with gestational diabetes alone. METHODS: This population-based cohort study included administrative data on all women who gave birth in Ontario, Canada, during 2002-2015. Maternal/neonatal outcomes were compared across groups using logistic regression, adjusting for confounders. A nested case control study compared women with undiagnosed type 2 diabetes with women with gestational diabetes alone to determine risk factors that would help identify these women. RESULTS: Among 995 990 women, 68 163 had gestational diabetes (6.8%) and, of those women with gestational diabetes,1772 had undiagnosed type 2 diabetes (2.6%). Those with undiagnosed type 2 diabetes were more likely to be older, from a lower income area, have parity > 3 and BMI ≥ 30 kg/m2 compared with gestational diabetes alone. Infants had a higher risk of perinatal mortality (OR 2.3 [1.6-3.4]), preterm birth (OR 2.6 [2.3-2.9]), congenital anomalies (OR 2.1 [1.7-2.5]), neonatal intensive care unit admission (OR 3.1 [2.8-3.5]) and neonatal hypoglycaemia (OR 406.0 [357-461]), which were similar to women with pre-existing diabetes. The strongest predictive risk factors included early gestational diabetes diagnosis, previous gestational diabetes and chronic hypertension. CONCLUSIONS: Women diagnosed with gestational diabetes who develop diabetes within 1 year postpartum are at higher risk of adverse pregnancy outcomes, including perinatal mortality. This highlights the need for earlier diagnosis, preferably pre-pregnancy, and more aggressive treatment and surveillance of suspected type 2 diabetes during pregnancy.