Brachial plexus injuries are among the most recognized complications associated with shoulder dystocia. They affect the nerves controlling a newborn's shoulder, arm, and hand. Some injuries resolve naturally, while severe nerve damage may cause permanent weakness and require specialized treatment.
Understanding the brachial plexus
The brachial plexus is a network of nerves extending from the spinal cord through the neck and shoulder.
It contains nerve roots known as C5, C6, C7, C8, and T1.
These nerves help control movement and sensation in the upper limb.
The upper roots contribute to shoulder lifting and elbow bending.
Lower roots are important for wrist and hand function.
When the nerves are injured, a baby may have difficulty moving certain parts of the arm.
The pattern of weakness depends on which nerves are affected.
How shoulder dystocia can cause nerve injury
Shoulder dystocia occurs when the baby's shoulder becomes trapped during vaginal delivery.
Mechanical forces may stretch the nerves between the neck and shoulder.
A nerve injury may occur during the obstruction or while delivery is being completed.
Excessive traction on the baby's head or neck can increase the risk of injury.
However, not all brachial plexus injuries are caused by excessive traction.
Some occur without recognized shoulder dystocia or improper medical management.
Determining the cause requires careful evaluation of the delivery circumstances.
Erb's palsy after shoulder dystocia
Erb's palsy is a common type of brachial plexus birth injury.
It usually affects the C5 and C6 nerve roots.
These nerves control important shoulder and elbow muscles.
A newborn with Erb's palsy may have difficulty lifting the arm or bending the elbow.
The affected arm may rest close to the body, with the shoulder turned inward.
This is sometimes described as the waiter's tip posture.
Hand grasp may remain normal.
More extensive brachial plexus injuries
Some injuries affect additional nerve roots.
A baby may have weakness in the wrist or hand as well as the shoulder.
Global brachial plexus palsy affects the entire or nearly entire nerve network.
The arm may have very little movement.
These injuries generally require closer specialist evaluation.
Severe nerve damage may involve rupture or avulsion.
An avulsion occurs when a nerve root is separated from its attachment near the spinal cord.
Recognizing symptoms after delivery
Parents may notice that their baby moves one arm less than the other.
The affected shoulder may appear weak.
The elbow may remain unusually straight.
The newborn's startle reflex may be reduced on one side.
Doctors also examine the collarbone and upper arm because fractures can cause pain-related movement restriction.
A baby with unexplained arm weakness should receive prompt medical assessment.
Treatment and rehabilitation
Mild nerve stretching injuries often improve during the first months of life.
Physical therapy may help maintain joint flexibility.
Occupational therapy can support functional movement as the child grows.
Children with persistent weakness may need specialist assessment for nerve surgery.
Procedures such as nerve grafting or nerve transfer may be considered in selected severe cases.
The timing depends on the injury pattern and recovery.
Long-term outcomes
Some children recover normal arm movement.
Others experience lasting shoulder weakness, limited rotation, or reduced hand function.
Persistent muscle imbalance can contribute to joint stiffness.
Early identification and appropriate follow-up help clinicians manage these complications.
Common questions around shoulder dystocia nerve injuries
Does shoulder dystocia always cause Erb's palsy?
No. Many babies experience shoulder dystocia without nerve damage.
Can a brachial plexus injury heal naturally?
Yes. Mild injuries often improve without surgery.
Can severe nerve injuries cause permanent disability?
Yes. Some children experience lasting weakness or movement restrictions.
