Shoulder dystocia is a delivery complication where the baby’s shoulder gets stuck behind the mother’s pelvic bone after the head has already been born. It happens in roughly 0.6% to 1.4% of vaginal deliveries when babies are average-sized, but the rate climbs to 5% to 9% when babies weigh more than about 8 pounds, 13 ounces at birth. It’s classified as an obstetric emergency because the baby’s body needs to be delivered quickly once the head is out.
How It Happens During Delivery
During a typical vaginal birth, the baby’s head delivers first, and the shoulders follow within the next contraction or two by naturally rotating to fit through the pelvis. In shoulder dystocia, that rotation fails. The baby’s front shoulder catches on the pubic symphysis, the firm ridge of bone at the front of the mother’s pelvis. Less commonly, the back shoulder gets caught on the sacral promontory, a bony ledge at the base of the spine.
The first visible sign is often called the “turtle sign.” After the baby’s head emerges, it retracts back tightly against the mother’s body, as though pulling back in. This happens because the shoulder is jammed and preventing the baby from moving any further out. At that point, the delivery team recognizes that routine delivery maneuvers won’t work and shifts into an emergency response. Time matters because the umbilical cord can be compressed between the baby and the pelvic bones, reducing oxygen flow.
What the Delivery Team Does
The response to shoulder dystocia follows a practiced sequence of maneuvers, moving from least to most invasive. The first step is typically repositioning the mother: her legs are flexed sharply toward her abdomen, which changes the angle of the pelvis and creates more room. At the same time, an assistant may apply firm downward pressure just above the pubic bone to try to push the baby’s shoulder free.
If that doesn’t work, the team moves to internal maneuvers. These involve reaching inside and either rotating the baby’s shoulders to a different angle or delivering the back arm first to reduce the width of the shoulders passing through. In rare cases where none of these techniques succeed, more aggressive interventions are needed. The entire process typically unfolds within minutes, guided by protocols that delivery teams rehearse regularly through simulation drills.
Risk Factors
The single biggest risk factor is a large baby, a condition called fetal macrosomia. Current guidelines in North America and the UK flag babies with an estimated weight above 5,000 grams (about 11 pounds) in non-diabetic mothers, or above 4,500 grams (about 9 pounds, 15 ounces) in mothers with diabetes, as candidates for a planned cesarean section to avoid the risk entirely.
Maternal diabetes, both gestational and pre-existing, independently raises the risk because it tends to produce larger babies with a particular body composition: proportionally bigger shoulders and trunk relative to the head. Other factors that increase the likelihood include a previous delivery complicated by shoulder dystocia, maternal obesity, a pregnancy that extends past 40 weeks, and a prolonged second stage of labor. That said, about half of shoulder dystocia cases occur in babies of normal birth weight with no identifiable risk factors, which is part of what makes it difficult to predict.
Risks to the Baby
The most common injury to the baby is brachial plexus palsy, damage to the network of nerves that runs from the neck through the shoulder and down the arm. This can happen when the nerves are stretched during the delivery. Historically, about 12% of shoulder dystocia deliveries resulted in this type of nerve injury, but that rate has dropped to around 5.7% with improved training and standardized protocols.
The severity of the nerve damage varies widely. The mildest form involves a temporary disruption to the nerve’s outer coating, which typically resolves fully within weeks. More serious injuries involve actual tearing of nerve fibers, where some function returns over months but recovery may be incomplete. The most severe cases involve nerves being torn away from the spinal cord, which won’t heal on their own.
Recovery depends on which nerves are affected and how badly. For infants with injuries limited to the upper nerves (Erb’s palsy, the most common pattern), full recovery rates range from 69% to 95%. One large study found that persistent nerve damage at 12 months dropped from 1.9% to just 0.2% of shoulder dystocia cases after hospitals implemented structured training programs. Infants who haven’t regained biceps function by 3 months of age are typically evaluated for surgical nerve repair, which current evidence supports as effective when done early. Overall, about 20% to 30% of affected infants have some lasting deficit, though many of these are mild.
Bone fractures, most often to the collarbone, can also occur. These generally heal well in newborns without long-term problems. The most serious risk is oxygen deprivation if the delivery takes too long, though this outcome is rare when the condition is recognized and managed promptly.
Risks to the Mother
Shoulder dystocia carries real risks for mothers as well. Postpartum hemorrhage, heavier-than-normal bleeding after delivery, occurs in about 5% of affected deliveries compared to 2.8% of uncomplicated ones. Severe perineal tearing (third- or fourth-degree lacerations, meaning tears that extend into the muscle or tissue around the rectum) affects about 6.5% of mothers who experience shoulder dystocia, compared to 2.7% in deliveries without it. That translates to roughly 2.8 times the risk of significant tearing. These injuries require repair and can extend recovery time, but they do heal with appropriate care.
What Recovery Looks Like
For mothers, recovery after shoulder dystocia depends largely on whether tearing occurred and how extensive it was. Many women recover on a timeline similar to any vaginal delivery. Those with significant lacerations may need several additional weeks of healing and sometimes pelvic floor physical therapy.
For babies born without injury, there’s typically no difference from any other newborn. When brachial plexus palsy is present, the affected arm may appear limp or have limited movement. Infants who show full recovery within the first month are managed with gentle range-of-motion exercises. Those who still have weakness at one month should be seen by a specialized team. If elbow flexion hasn’t returned by three months, surgical options are considered. The window for the best surgical outcomes is early, generally within the first several months of life, so prompt referral matters.
For families who’ve experienced shoulder dystocia, the risk of recurrence in a future vaginal delivery is elevated. This is one of the factors providers weigh when discussing delivery planning for subsequent pregnancies, and a planned cesarean is sometimes recommended depending on the severity of the prior event and the estimated size of the next baby.