Usual Cause of Clavicular Fracture in a Neonate
The usual cause of clavicular fracture in a neonate is birth trauma during vaginal delivery, particularly in the setting of shoulder dystocia, macrosomia, or difficult extraction of the shoulders.
Mechanism and Context
Neonatal clavicular fractures occur as a direct consequence of the mechanical forces applied during the birth process. The fracture typically results from compression of the shoulder girdle as it passes through the birth canal, or from lateral traction applied to deliver the shoulders after the head has emerged 1. The anterior shoulder is the predominant site of fracture 2.
Key Risk Factors
The evidence consistently identifies several maternal and neonatal factors that increase fracture risk:
Neonatal factors:
- Birth weight >3,500-3,800g - This is the single most significant predictor 3, 4, 2
- Male gender 4
- Lower head-to-abdominal circumference ratio (indicating relatively larger body/shoulders) 2
- Macrosomia (birth weight >4,000-4,500g) 1, 5
Delivery factors:
- Spontaneous vaginal delivery with difficult shoulder extraction 3, 2
- Prolonged second stage of labor 3
- Assisted vaginal delivery (vacuum extraction, forceps) - increases risk 2.3-fold 4, 6
- Shoulder dystocia - though fractures occur even without this complication 1, 5
Maternal factors:
Important Clinical Distinctions
When Birth Trauma is NOT the Cause
While birth trauma accounts for the vast majority of neonatal clavicular fractures, clavicular fractures have low specificity for child abuse in the neonatal period 7. The guidelines specifically note that clavicular fractures fall into the "common, but low specificity" category for abuse 7.
For infants ≤10 days old with acute clavicular fracture and no history of trauma, skeletal survey is of uncertain appropriateness 8. This reflects the understanding that birth trauma is the overwhelmingly likely explanation in this age group.
Protective Factors
Cesarean section delivery is protective, with an odds ratio of 0.149 4. Notably, none of the 704 newborns delivered by cesarean section in one study had clavicular fractures 6, and only 8 of 92 fractures (9%) in another series occurred after cesarean delivery 3.
Clinical Significance
The incidence ranges from 0.26% to 1.11% of all live births 3, 2, 5, making it the most commonly fractured bone during the birth process 3.
The prognosis is universally excellent - all studies report complete recovery without complications 3, 2, 5. Even when accompanied by brachial plexus injury (Erb's palsy), which occurs in a small minority of cases, recovery is typically complete 3. Only 1 of 244 injured newborns in one series had permanent brachial plexus palsy 6.
Detection
- 77-87% of cases are detected by physical examination before hospital discharge 3
- 23% are recognized incidentally on chest X-ray 3
- 11% are discovered at routine follow-up visits after discharge 3
Bottom Line
Neonatal clavicular fracture is an unavoidable consequence of the mechanical forces of vaginal delivery, particularly when the infant is large relative to the maternal pelvis. The fracture occurs from compression or traction forces on the shoulder girdle during passage through the birth canal. While certain risk factors (especially birth weight >3,500g) increase the likelihood, these fractures can occur even in uncomplicated deliveries of normal-weight infants 2, 5. The injury is transient with uniformly excellent outcomes, requiring only parental reassurance and routine follow-up 3.