Shoulder dystocia !

Shoulder dystocia is an emergency at birth when the baby's head is out but a shoulder is stuck behind the mother's pubic bone.

Updated 2026-11-01

Structures involved

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What it is

An obstetric emergency in which, after delivery of the fetal head, gentle downward traction fails to deliver the shoulders because the anterior shoulder is impacted behind the maternal pubic symphysis (or, less often, the posterior shoulder on the sacral promontory). It requires additional manoeuvres to deliver the baby.

Who gets it

Complicates roughly 0.2–3% of vaginal births, more often with heavier babies. Most cases occur in babies of normal weight and cannot be predicted, so every birth attendant must be ready to manage it.

Causes

Mismatch between the size of the fetal shoulders and the maternal pelvis
Fetal shoulders failing to rotate into the wider oblique diameter of the pelvis

Risk factors

Fetal macrosomia (large baby)
Maternal diabetes, including gestational diabetes
Maternal obesity and excessive weight gain in pregnancy
Previous shoulder dystocia
Post-term pregnancy
Prolonged second stage of labour and operative vaginal delivery (vacuum or forceps)

Pathophysiology

Normally the shoulders enter the pelvic inlet in an oblique diameter and rotate under the pubic arch. If the bisacromial diameter is large, or rotation fails, the anterior shoulder lodges behind the pubic symphysis. The umbilical cord is compressed between the fetal body and the pelvis, so fetal pH and oxygen fall with every minute of delay. Excessive lateral traction on the head stretches the brachial plexus.

Symptoms and signs

Head delivers but then retracts against the perineum (turtle sign)
Failure of restitution (the head does not rotate)
Shoulders do not deliver with usual gentle downward traction

Diagnosis

Clinical: Clinical diagnosis at delivery: the turtle sign and failure to deliver the shoulders with routine traction. The time of head delivery is noted and help is called immediately.
Tests: Umbilical cord blood gases after birth to assess fetal acidosis; neonatal examination for injury.
Imaging: Not used to diagnose it. After birth, radiographs of the clavicle and humerus if fracture is suspected. Antenatal ultrasound estimates of fetal weight are imprecise for prediction.

Differential diagnosis

Large fetal body or abdomen (fetal anomalies such as tumours or ascites)
Short umbilical cord or cord entanglement
Conjoined twins or locked twins (rare)

Goal of treatment

Free the impacted shoulder quickly and safely, using a set sequence of manoeuvres, to deliver the baby before hypoxic injury, while avoiding excessive traction on the head.

Treatment

Acute: Call for help (obstetrician, neonatal team, anaesthesia), note the time, stop maternal pushing, avoid fundal pressure and avoid pulling hard on the head; consider episiotomy to make room for internal manoeuvres.
Procedure: First-line: McRoberts manoeuvre (hyperflexing the mother's thighs onto her abdomen) with suprapubic pressure over the anterior shoulder.
Procedure: If unsuccessful: delivery of the posterior arm, internal rotational manoeuvres (Rubin, Woods screw), or the all-fours (Gaskin) position.
Surgical: Last-resort measures when others fail: deliberate fracture of the clavicle, symphysiotomy or cephalic replacement (Zavanelli) followed by caesarean section.
Follow-up: Nursing priorities: time keeping and clear documentation of manoeuvres and times, positioning the mother, newborn resuscitation readiness, examination of the baby's arms and clavicles, and watching the mother for postpartum haemorrhage and perineal tears.

Complications

Neonatal brachial plexus injury (Erb palsy, C5–C6)
Fracture of the clavicle or humerus
Hypoxic-ischaemic encephalopathy and neonatal death
Maternal postpartum haemorrhage
Third- and fourth-degree perineal tears
Uterine rupture and bladder injury (rare)

Prognosis

Most babies are delivered with first-line manoeuvres without lasting harm. Most brachial plexus injuries recover within months, but a minority are permanent. The risk of shoulder dystocia is higher in later pregnancies.

Prevention

Good control of diabetes in pregnancy
Healthy weight gain in pregnancy
Discussing planned caesarean section when the estimated fetal weight is very high, especially with diabetes
Regular team drills (simulation) for shoulder dystocia

Test yourself

Think of the answer, then tap the question to see it.

What is the turtle sign?

The fetal head delivers and then retracts against the perineum, suggesting shoulder dystocia.

What is the first-line manoeuvre?

McRoberts manoeuvre combined with suprapubic pressure.

Which actions must be avoided?

Fundal pressure and strong lateral or downward traction on the fetal head.

Which nerve injury is most common, and which roots are involved?

Erb palsy, an upper brachial plexus injury of C5–C6.

What are two major risk factors?

Fetal macrosomia and maternal diabetes (also obesity, post-term pregnancy and previous shoulder dystocia).

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: What are some common complications during labor and delivery? (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), 2024); Brachial plexus injury in newborns (MedlinePlus (U.S. National Library of Medicine), 2024).

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Representative model, for educational purposes only.

Pubic symphysis highlighted on the Durgical 3D model