Erb’s palsy risk factors fall into two camps: birth mechanics (shoulder dystocia, macrosomia, delivery technique) and maternal health (gestational diabetes, preeclampsia). Understanding both is the first step toward prevention.
The honest version of this subject has two halves that sound contradictory. The risk factors do not predict who this happens to. And training the delivery team to respond changed the injury rate from 7.4% to 1.3%.
Take the first half first, because a lot of writing on this topic gets it wrong. The American College of Obstetricians and Gynecologists convened a task force on neonatal brachial plexus palsy, and its executive summary records that multiple peer-reviewed reports describe the injury occurring without any clinically recognizable shoulder dystocia, at both vaginal and cesarean delivery. The injury affects about 1.5 per 1,000 total births, and a screening list will not tell you which 1.5.
The second half is where the useful part lives. Our Erb’s palsy overview covers the condition itself.
The recognized associations are real. What they are not is predictive, and holding both facts at once is the only accurate position.
Shoulder dystocia, where the baby’s shoulder lodges behind the pubic bone after the head has delivered, is the association most often named. Macrosomia, maternal diabetes, operative vaginal delivery with forceps or vacuum, and a previous delivery complicated by shoulder dystocia all appear on the list as well. Each raises the odds.
The problem is arithmetic. The injury occurs in roughly 1.5 per 1,000 births, so even a factor that multiplies risk several times over still leaves the overwhelming majority of babies with that factor unaffected, while a substantial share of affected babies have no factor at all. That is why the task force stops short of endorsing risk-factor screening as prevention, and why a delivery record with no noted risk factor does not settle anything either.
It is an obstetric emergency with a defined response. The shoulder is impacted, the clock is running, and a sequence of maneuvers exists to free it: repositioning the mother’s legs, applying pressure above the pubic bone, rotating the baby internally, delivering the posterior arm. What the maneuvers have in common is that none of them involves pulling harder on the head, which is the instinct they are designed to replace.
Prediction fails and preparation works. That is a strange sentence to write about an obstetric injury, and there is a twelve-year study behind it.
Southmead Hospital in Bristol, delivering around 6,000 babies a year, introduced a multi-professional training day that included a 30-minute practical session on shoulder dystocia. Researchers then compared three four-year periods: before training, early training, and a decade later. Use of at least one recognized resolution maneuver rose from 46.3% of cases to 92% and then to 99.8%.
Brachial plexus injury at birth fell alongside it, from 24 of 324 cases of shoulder dystocia (7.4%) before training, to 6 of 262 (2.3%) in the early period, to 7 of 562 (1.3%) a decade in. The finding the authors put in their conclusion is the one worth repeating: in those 562 later cases of shoulder dystocia, there were no brachial plexus injuries lasting longer than twelve months.
Nothing in that study screened a single mother. It trained the people in the room to do the right thing quickly when something unpredictable happened, which is a different model of prevention and a better fit for this injury. Our page on prevention strategies covers what that looks like in practice.
Ordered by what the evidence supports:
Cesarean delivery lowers the risk. It does not remove it, and the same task force report is the reason we can say that plainly.
Cases of neonatal brachial plexus palsy are described in the literature following cesarean delivery as well as vaginal delivery, which means the injury is not exclusively a product of the descent through the birth canal. That matters for two audiences. For a family weighing a planned cesarean on the strength of an estimated fetal weight, it means the operation is a reduction in risk rather than a guarantee, and it carries its own recovery. For anyone reviewing a case afterwards, it means the route of delivery is evidence rather than proof.
Operative vaginal delivery with forceps or vacuum sits in a different position. Instrumentation is associated with higher rates, and the judgment calls around when to use it, when to stop, and when to convert are exactly the ones that get examined later.
Maternal health acts on this injury mostly through one mechanism, which is how big the baby gets.
Diabetes in pregnancy, whether pre-existing or gestational, drives fetal growth, and a larger baby has broader shoulders relative to the birth canal. Glucose control is therefore the intervention with the clearest path to the outcome, and it works months before the delivery room rather than during it. Maternal obesity and excessive gestational weight gain feed the same pathway.
Preeclampsia belongs to a different story. It restricts placental blood flow and its risks run toward growth restriction, prematurity and the timing of delivery, rather than toward a shoulder impacted at birth. Grouping it with the mechanical risk factors, as a lot of writing does, muddles two separate problems that need different management.
When providers fail to identify or respond to known risk factors and a child develops Erb’s palsy, families may have a legal claim. Specialized birth injury lawyers can review your case at no cost.
Shoulder dystocia, macrosomia, maternal diabetes, operative vaginal delivery and a previous delivery complicated by shoulder dystocia are the recognized associations. None of them predicts who is affected. The injury occurs in about 1.5 per 1,000 births, so most babies with a risk factor are unaffected and many affected babies have no risk factor at all.
Yes. The ACOG task force records cases of neonatal brachial plexus palsy described in the literature following cesarean delivery as well as vaginal delivery. A planned cesarean lowers the risk rather than removing it, which matters both for a family weighing one and for anyone reviewing a case afterwards.
By preparing the team rather than screening the mother. Over twelve years at one UK hospital delivering 6,000 babies a year, shoulder dystocia training raised the use of recognized resolution maneuvers from 46.3% of cases to 99.8%, and brachial plexus injury at birth fell from 7.4% to 1.3%. In the 562 later cases, none of the injuries lasted beyond twelve months.
Because the shoulder is impacted behind the pubic bone while the head has already delivered, and the instinctive response, pulling harder on the head, is the one that stretches the brachial plexus. The defined maneuvers exist to free the shoulder without that traction, which is why rehearsing them changes outcomes.
Yes, and it is the part most often examined afterwards. Instrumented delivery with forceps or vacuum is associated with higher rates, and the judgment calls about when to use an instrument, when to stop, and when to convert are the ones a case review focuses on. What technique cannot do is make an unpredictable injury predictable.
Effectively, yes. The task force position is that this injury occurs without recognizable shoulder dystocia and at cesarean delivery, so no screening strategy identifies the affected births in advance. That is a reason to invest in trained response rather than a reason to accept the injury, and it is also why a delivery record showing no risk factors settles nothing on its own.
Kelsey is an experienced surgical nurse who works extensively with pediatric patients and families navigating birth injuries and cerebral palsy diagnoses. She is licensed by the Missouri Board of Nursing and operates under the Nurse Licensure Compact, allowing her to practice across compact-member states. As both a mentor and patient advocate, Kelsey focuses on safety, communication, and compassionate care: helping families understand medical procedures, treatment options, and the realities of pediatric conditions.
View Kelsey Pabst, RN's full bio →
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