Birth injuries are an uncommon complication of vaginal and cesarean delivery. Injuries range from those that are minor and require no further diagnostic evaluation or treatment to those that are life threatening or associated with long-term morbidity. Risk factors for injury include macrosomia, precipitous or prolonged delivery, breech presentation, cephalopelvic disproportion, shoulder dystocia, and the use of forceps or vacuum to assist extraction. However, birth injuries also occur in infants with no identifiable risk factors, making prediction difficult.
Fractures as complications of the delivery process most commonly occur in the clavicle, humerus, and femur. Skull fractures are also reported, usually in association with forceps delivery. Long bone fractures generally require evaluation by an orthopedic specialist, whereas skull fractures are usually simple linear fractures that do not require intervention. Infants rarely have more than one fracture; for those with multiple fractures, diagnoses such as osteogenesis imperfecta should be considered.
Clavicle fractures occur as a complication of the delivery process in approximately 0.5%1 to 1.7%2 of all live births. Historically, clavicle fractures were thought to be a result of obstetric mismanagement. Recent studies, however, have shown that little can be done to prevent this complication. Clavicle fractures are most commonly reported with vaginal deliveries, but they are also reported with cesarean sections. Risk factors include fetal macrosomia, instrumented delivery, and a prolonged second stage of labor, but predictive models based on these factors have a high false-positive rate and have not been clinically useful.
The humerus is occasionally fractured during the delivery process, typically with a difficult vertex delivery of the shoulder or a breech delivery. The fracture may result from direct pressure or traction. A greenstick fracture is most common, but displaced fractures may also occur. Breech deliveries may also result in a femur fracture; most are complete fractures that result in obvious deformity.
Clavicular fractures are sometimes overlooked, particularly in the case of a nondisplaced fracture. Acutely, the examiner may feel crepitus, and irritability may be noted with pressure over the bone. In displaced fractures, a bony ledge may be palpated. The infant may have decreased movement of the ipsilateral arm with an asymmetric Moro response. This pseudoparalysis is typically related to pain but may also be the result of associated nerve damage. Frequently, the fracture is first diagnosed as normal healing occurs and the callus forms, which may be noted as early as the second week of life.
Humerus fractures may present clinically with swelling and pain; in the case of a displaced fracture an obvious deformity will be noted. The infant may refuse to move the affected arm, thereby resulting in an asymmetric Moro reflex and pseudoparalysis; however, nerve involvement may also occur. Most femur fractures will present as an obvious deformity.