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Meta-analysis Results: Do Shoulder Dystocia Simulations Reduce the Prevalence of Neonatal Brachial Plexus Palsy?


  • Guidelines aimed at reducing neonatal brachial plexus palsy (NBPP) due to shoulder dystocia suggest use of simulation exercises (with mannequins) 
  • Wagner at al. (AJOG, 2021) evaluated the outcomes associated with the implementation of simulation exercises to reduce NBPP with shoulder dystocia 


  • Systematic review and meta-analysis 
  • Study inclusion criteria 
    • Frequency of shoulder dystocia  
    • Associated complications before and after the implementation of interventional exercises  
  • Study design 
    • Study effects were combined using a Bayesian meta-analysis and were reported as risk ratios and 95% credible intervals (Crs) 
  • Primary outcomes 
    • NBPP diagnosed following deliveries complicated by shoulder dystocia 
    • Presence of brachial palsy at 12 months or later 
  • Secondary outcomes 
    • Frequency of shoulder dystocia 
    • Cesarean delivery 


  • 16 studies | 428,552 deliveries 
    • Deliveries during preintervention guideline period: 50.8% 
    • Deliveries during postintervention period: 49.2% 
  • The incidence of neonatal brachial plexus palsy after shoulder dystocia decreased from preintervention to postintervention period  
    • Preintervention period: 12.1%  
    • Postintervention period: 5.7% 
    • Risk ratio (RR) 0.37 (95% Cr, 0.26 to 0.57); probability of reduction 100% 
  • The overall proportion of neonatal brachial plexus palsy decreased  
    • Preintervention period: 0.3% 
    • Postintervention period: 0.1% 
    • RR 0.53 (95% Cr, 0.21 to 1.26); probability of reduction 94% 
  • 2 studies followed newborns with brachial plexus palsy for at least 12 months reported conflicting data  
    • Study 1: Reduction in persistent NBPP following integration of guideline interventions 
      • Preintervention: 1.9% 
      • Postintervention: 0.2% 
      • RR 0.13 (95% CI, 0.04 to 0.49) 
    • Study 2: No difference in persistent NBPP 
      • Preintervention: 0.3 per 1000 births 
      • Postintervention: 0.2 per 1000 births 
      • RR 0.77 (95% CI, 0.31 to 1.90) 
  • Following the implementation of shoulder dystocia interventional exercises, the diagnosis of shoulder dystocia increased significantly 
    • Preintervention: 1.2% 
    • Postintervention: 1.7% 
    • RR 1.39 (95% Cr, 1.19 to 1.65); probability of increase 100% 
  • Compared with the preintervention period, the cesarean delivery rate increased postimplementation 
    • Preintervention: 21.2% 
    • Postintervention: 25.9% 
    • RR 1.22 (95% Cr, 0.93 to 1.59); probability of increase 93% 


  • There was a 63% risk reduction for newborn brachial plexus palsy after the introduction of shoulder dystocia simulation exercises   
  • However, introduction of simulation exercises also increased the diagnosis of shoulder dystocia diagnoses by 39% and cesarean delivery by 22%  
  • Study limitations 
    • In many studies, there was lack of matching and adjustment for confounding  
  • The authors state that the results of this study  

…demonstrate mixed clinical outcomes following introduction of shoulder dystocia simulation, indicate the need for a reassessment of the recommendations calling for the universal implementation of shoulder dystocia interventional exercises 

The uncertainties surrounding the nature of the interventional exercises and the necessary audience, the potential unintended consequences, the questionable improvement in the long-term sequelae of shoulder dystocia along with resource utilization and cost-effectiveness together construct a compelling reason to undertake an adequately powered trial that incorporates long-term follow-ups 

Wagner at al. (AJOG, 2021)

Learn More – Primary Sources:

Interventions to decrease complications after shoulder dystocia: a systematic review and Bayesian meta-analysis 


Shoulder Dystocia: Diagnosis, Evaluation and Management


Shoulder dystocia is an obstetrical emergency. While there are associated risk factors, they are poor at predicting shoulder dystocia. The majority of cases will occur in women without diabetes whose offspring are within normal weight range. Nor is there any evidence that shoulder dystocia can be prevented. Complications include PPH and brachial plexus injuries. ACOG published guidance in 2017 that has been reaffirmed (2019).

Diagnosis (ACOG):

Failure to deliver the fetal shoulder(s) with gentle downward traction on the fetal head, requiring additional obstetric maneuvers to effect delivery

Risk Factors

  • Maternal
    • Prior history of shoulder dystocia
      • Universal prophylactic cesarean section is not recommended
      • Due to recurrence risk (1% to 16.7%), evaluate EFW, GA, glucose and severity of previous event
      • Patient discussion and careful delivery planning are recommended
    • Diabetes: GDM and pre-gestational diabetes
  • Fetal
    • Macrosomia (see delivery recommendations below)
    • Large fetal chest relative to biparietal diameter (seen with diabetes)

Note: Despite known risk factors “…shoulder dystocia cannot be accurately predicted or prevented”


  • There are no ultrasound findings or labor patterns that are predictive of shoulder dystocia
  • The classic “turtle sign” is “…suggestive, but not diagnostic, of the presence of shoulder dystocia”
  • Diagnosis is based on clinical judgement when there is failure to deliver the fetal shoulders after initial traction attempts

Management  for Suspected Fetal Macrosomia (see Related ObG Topics below):

  • Delivery <39 weeks gestation is not recommended without medical indication
  • Elective cesarean delivery should be considered for the following
    • Without diabetes: estimated fetal weight of ≥5,000 gm
    • With diabetes: estimated fetal weight of ≥4,500 gm
  • Induction
    • Not suggested for suspected fetal macrosomia as induction has not been shown to improve maternal or fetal outcomes
  • Trial of labor
    • Suspected fetal macrosomia is not a contraindication to a trial of labor after cesarean delivery

Maneuvers (see videos in ‘Learn More – Primary Sources’ below):

  • McRoberts maneuver: Best first step (Level B Evidence)
    • Maternal knees flexed and brought to chest while suprapubic pressure is applied
  • Posterior Shoulder Delivery to reduce shoulder diameter
    • Next option if McRoberts unsuccessful
    • Decreases the diameter of the fetal shoulder girdle
  • Additional techniques to deliver the posterior shoulder include the following
    • Rubin maneuver: Place hand on the back of the posterior fetal shoulder followed by anterior rotation towards the fetal face
    • Woods Screw maneuver: Apply pressure to anterior surface of the posterior shoulder with fetal rotation until anterior shoulder disengages from behind the maternal symphysis
    • Posterior axilla sling traction: Thread a size 12 or 14 French soft catheter around the posterior shoulder and apply moderate traction to the sling to deliver the shoulder
    • Gaskin all-fours maneuver (for women without anesthesia): With patient on hands and knees, apply gentle downward traction on the posterior shoulder or upward traction on the anterior shoulder
  • ‘Last Resort’ maneuvers: Associated with significant maternal and/or fetal morbidity and mortality
    • Zavanelli maneuver: Head placed back in vaginal canal followed by cesarean section
    • Abdominal rescue: shoulder dislodged from above via hysterotomy
    • Intentional fetal clavicular fracture

Additional Considerations:

  • Do not apply fundal pressure due to risk for uterine rupture
  • Instruct patient to stop pushing until dystocia is resolved
  • Evidence does not support use of routine episiotomy
    • Reserve for clinical situation where additional room may be needed for above maneuvers
  • Documentation should be contemporaneous and include
    • Time of diagnosis
    • Management
    • Time of delivery
    • Sequelae
  • Simulation Programs
    • Simulation is used to train healthcare personnel for particularly severe, high acuity events that are relatively infrequent
    • Simulation is effective in the setting of shoulder dystocia and improves
      • Communication | Use of maneuvers | Documentation

Note: Maneuvers may be repeated if not successful initially and in addition

…clinicians should use the maneuver most likely to result in successful delivery

No randomized controlled trials have compared maneuvers for shoulder dystocia alleviation

Brachial plexus injury can occur regardless of the procedures used to disimpact the shoulder(s) because all maneuvers can increase the degree of stretch on the brachial plexus

Learn More – Primary Sources

ACOG Practice Bulletin 178: Shoulder Dystocia

Johns Hopkins Medicine | Gynecology & Obstetrics: Shoulder Dystocia Simulation and Training Videos

Macrosomia: Determination of EFW and Recommendations for Delivery


The term fetal macrosomia implies growth beyond an absolute birth weight of 4000 grams or 4500 grams, regardless of gestational age. The risk of morbidity for both infants and mothers increases when the birthweight is between 4000 and 4500 grams. Risks for maternal and newborn morbidity rise considerably with birthweights >4500g. A correct diagnosis can only be made after weighing an infant at birth, as ultrasound prediction is not precise.


  • Consider a prophylactic cesarean for suspected fetal macrosomia if the EFW (estimated fetal weight) is > 5000 grams in women without diabetes
  • Consider a prophylactic cesarean for suspected fetal macrosomia if the EFW is > 4500 grams in women with diabetes
  • Induction before 39w0d is not suggested for suspected fetal macrosomia as induction has not been shown to improve maternal or fetal outcomes
  • Suspected fetal macrosomia is not a contraindication to a trial of labor after cesarean


In the United States, 7.8% of all live-born infants weigh > 4000 grams and 1% weigh > 4500 grams. The most serious complication of fetal macrosomia is shoulder dystocia which complicates 0.2-3.0% of all vaginal deliveries. When the birthweight is > 4500 grams, the shoulder dystocia rate increases to 9-14%. The shoulder dystocia rate increases to 20-50% in the presence of maternal diabetes when the birthweight is > 4500 grams.  ‘Large for gestational age (LGA)’ also refers to excessive fetal growth, but rather than absolute weight, LGA is usually defined as ≥90th percentile for a given gestational age.


Risk Factors for Macrosomia

  • Preexisting maternal diabetes
  • Uncontrolled gestational diabetes
  • Excessive gestational weight gain
  • Excessive inter pregnancy weight gain
  • Prior macrosomic infant
  • Post-term pregnancy
  • Maternal nonsmoking status

Maternal Risks Associated with Macrosomia

  • Increased risk of cesarean delivery
  • Postpartum hemorrhage
  • Vaginal lacerations

Fetal Risks Associated with Macrosomia

  • Shoulder dystocia leading to brachial plexus injury or clavicular fracture
  • Decreased 5 minute Apgar score
  • Increased rates of admission to the NICU, including longer stays
  • Obesity later in life

Accuracy of EFW Measurement

  • Fundal height
    • “Poor predictor of macrosomia”: Better at ruling out than identifying macrosomia
    • Sensitivity: 29% to 70%
    • Specificity: >90%
  • Abdominal palpation maneuvers
    • Sensitivity: 16% to 68%
    • Specificity: 90% to 99%
    • PPV: 38% to 80%
  • In women with diabetes
    • “Clinical estimates of macrosomia are as predictive as those derived with ultrasonography”
  • Ultrasound
    • Prediction of birth weight >4,500g
      • Sensitivity: 10% to 45%
      • Specificity: 57% to 99%
      • PPV: 11% to 44%
      • NPV: 92% to 99%
    • Prediction of birth weight >4,000g
      • Sensitivity: 56%
      • Specificity: 92%
    • Hadlock estimation
      • Newborns>4,500 g: Mean absolute percent error of 13% | Increases with greater EFW
      • Nonmacrosomic newborns: Mean absolute percent error of 8%

Note: Upon review of current literature, ACOG states

No single formula based on ultrasound biometry performs significantly better than others for the detection of macrosomia more than 4,500 g

Similar to clinical estimates of fetal weight, ultrasonography can be used most effectively as a tool to rule out macrosomia, which may help avoid maternal and fetal morbidity

Learn More – Primary Sources:

ACOG Practice Bulletin No. 216 : Macrosomia