Obstetric shoulder injury. Associated risk factors, prediction and prognosis.

A prospective case-control study was made to estimate the incidence of clavicular fracture and brachial plexus palsy, to find out possible risk factors during pregnancy and labor associated with these injuries, and to ascertain the prognosis of injured infants. Clavicular fracture occurred in 165 (3.2%) and brachial plexus palsy in 10 (0.2%) of the 5082 infants born during the study period. From maternal characteristics the Body Mass Index (kg/m2) and pregnancy weight gain were significantly greater in the cases than in the controls. Symphysis-to-fundus height was, on average, higher in the case group. There were no more instrumental vaginal deliveries in cases than in controls. The shoulder injured infants were in every way bigger, but only in 30% of the cases macrosomic (birthweight over the 90th percentile), and they were more often males than in the controls. The prediction of shoulder injury by ultrasound was not successful in our study. The prognosis of injured infants was good, all children except one recovered soon after birth.