Shoulder dystocia is a birth complication where the baby’s head delivers normally but one or both shoulders get stuck behind the mother’s pelvic bone, preventing the rest of the body from following. It occurs in roughly 1 in 150 vaginal births, though rates range from 0.15% to 1.7% depending on the baby’s size. It’s unpredictable, often resolved within minutes, but requires fast action from the delivery team to prevent injury to the baby or mother.
How Shoulder Dystocia Happens
During a typical vaginal delivery, the baby’s shoulders rotate naturally to fit through the narrowest part of the pelvis. In shoulder dystocia, the baby’s front shoulder catches on the mother’s pubic bone instead of sliding beneath it. Less commonly, the rear shoulder can get caught on the sacrum (the curved bone at the base of the spine).
The first visible sign is sometimes called the “turtle sign.” The baby’s head delivers but then appears to pull back tightly against the mother’s body, like a turtle retreating into its shell. The head may also turn red or purple. At this point, the delivering clinician recognizes the shoulders aren’t following and the emergency response begins.
Risk Factors
The single strongest predictor is a large baby. The bigger the baby, the more likely the shoulders will be too broad to pass easily. The American College of Obstetricians and Gynecologists suggests that elective cesarean delivery may be considered when a baby’s estimated weight exceeds about 11 pounds (5,000 grams), or about 9 pounds 15 ounces (4,500 grams) in mothers with gestational diabetes.
Other factors that increase risk include:
- Gestational diabetes or maternal diabetes: both are associated with larger babies and a different pattern of fetal fat distribution, with more weight carried in the shoulders and trunk
- Maternal obesity
- A previous delivery complicated by shoulder dystocia
- Post-term pregnancy (going past 40 weeks)
- A prolonged or assisted second stage of labor, including deliveries requiring vacuum or forceps
That said, roughly half of shoulder dystocia cases occur in babies of normal weight with no identifiable risk factors. There is no reliable way to predict it in advance, which is why delivery teams train extensively for it even when a pregnancy looks uncomplicated.
What the Delivery Team Does
When shoulder dystocia is recognized, the room changes quickly. Additional staff are called in, and the team works through a series of physical maneuvers designed to free the baby’s shoulder. Many hospitals use a mnemonic called HELPERR to guide the response in order.
The first and most common maneuver is called McRoberts’ positioning. The mother’s thighs are sharply flexed up toward her abdomen with her knees bent toward her head. This lifts and rotates the entire pelvis, essentially raising the pubic bone up and over the baby’s trapped shoulder. It’s simple, noninvasive, and resolves many cases on its own.
At the same time, a member of the team applies firm pressure just above the mother’s pubic bone with a fist or the heel of the hand. This pushes the baby’s front shoulder off center and into an angled position, giving it room to slip through. The pressure is directed sideways, not downward.
If those two steps don’t work, the team moves to internal maneuvers. In Rubin’s maneuver, a hand is placed behind the baby’s shoulder blade and pressure is applied to rotate the shoulders into a diagonal position within the pelvis. The corkscrew maneuver (sometimes called the Woods’ screw) takes this further: both shoulders are rotated a full 180 degrees in a winding motion, threading the baby through like turning a screw.
Another option is delivering the baby’s rear arm first. The clinician reaches past the baby’s head, finds the rear arm, flexes the elbow, grasps the wrist, and sweeps the arm across the baby’s chest and out. This reduces the width of the shoulders enough for the body to deliver.
If none of these internal maneuvers succeed, the Gaskin maneuver has the mother flip onto her hands and knees. This changes the pelvic geometry and often allows the rear shoulder (now on top) to deliver first. In extremely rare cases where all maneuvers fail, more invasive surgical options are used.
Risks to the Baby
The most well-known complication is a brachial plexus injury, which is damage to the bundle of nerves running from the neck through the shoulder and into the arm. This happens when the nerves are stretched during delivery. The baby may have weakness or lack of movement in the affected arm. The presence of shoulder dystocia increases the risk of brachial plexus injury by roughly 100-fold compared to deliveries without it.
The good news is that most of these injuries heal. For the most common type, which affects the upper nerves (sometimes called Erb’s palsy), recovery rates range from 69% to 95%. However, about 20% to 30% of affected infants do not recover fully, and more severe injuries involving all the nerves from C5 through T1 leave persistent deficits in nearly 80% of cases at 18 months. Some children ultimately need surgery or long-term physical therapy.
Fractures of the collarbone are another possible injury, occurring in a small percentage of cases. These typically heal on their own within a few weeks. More serious but rare complications include oxygen deprivation if the delivery is significantly delayed, which can in very rare instances lead to brain injury.
Risks to the Mother
Shoulder dystocia carries real physical consequences for the mother as well. Postpartum hemorrhage (heavy bleeding after delivery) occurs in about 11% of cases. Fourth-degree perineal tears, the most severe kind that extend through the muscle and into the rectal lining, happen in about 3.8% of cases. These rates stay roughly the same regardless of which maneuvers are used to free the baby.
Other possible maternal injuries include third-degree tears, damage to the urethra or bladder, and in rare cases, separation of the pubic bone from prolonged positioning with the legs sharply flexed. Uterine rupture is an extremely rare but serious possibility.
Recovery After Shoulder Dystocia
For most mothers, recovery follows a similar path to any vaginal delivery, though it may take longer if significant tearing occurred. Third- and fourth-degree tears require surgical repair and can take weeks to months to fully heal, sometimes leaving lasting issues with urinary or fecal control that benefit from pelvic floor physical therapy.
For babies with a brachial plexus injury, the first few months are a watchful period. Pediatricians and sometimes pediatric neurologists monitor whether the baby is regaining movement in the affected arm. Most improvement happens in the first three to six months. If the baby isn’t showing signs of recovery by then, referral to a specialist for possible nerve surgery becomes more likely. Ongoing physical therapy and range-of-motion exercises are a standard part of care to prevent the joints from stiffening while the nerves heal.
Babies who had a clavicle fracture during delivery usually need no specific treatment beyond gentle handling. Parents may notice the baby favoring one side or crying when the arm on the affected side is moved, but the bone typically heals completely within a few weeks.
Can It Be Prevented?
Because shoulder dystocia is largely unpredictable, true prevention is difficult. Ultrasound estimates of fetal weight are notoriously imprecise, often off by 10% to 20% in either direction, which makes it unreliable as a screening tool. Many large babies deliver without any difficulty, and many cases of shoulder dystocia involve average-sized babies.
For mothers with gestational diabetes, careful blood sugar management throughout pregnancy helps reduce the likelihood of excessive fetal growth. When a baby is estimated to be very large, particularly in the context of diabetes, planned cesarean delivery may be discussed. But for the general population, routine cesarean delivery for suspected large babies is not recommended because the harms of unnecessary surgery outweigh the relatively low chance of shoulder dystocia.
The most effective “prevention” is really preparedness. Delivery teams that rehearse shoulder dystocia scenarios regularly respond faster and with better coordination when it happens. Simulation-based training has been shown to improve outcomes, which is why most labor and delivery units run these drills on a recurring basis.