Perinatal implications of shoulder dystocia.

OBJECTIVE: To assess the antecedents of shoulder dystocia, the risk of recurrence, and the perinatal morbidity associated with the different maneuvers used for its management.

METHODS: We conducted a 10-year (1980-1989) retrospective case record review of all instances of shoulder dystocia in a teaching maternity hospital.

RESULTS: There were 254 cases of shoulder dystocia in 40,518 vaginal cephalic deliveries (0.6%), with 33 cases (13.0%) of brachial plexus palsy and 13 fractures (5.1%). There were no perinatal deaths attributable to shoulder dystocia. The risk of shoulder dystocia was increased with prolonged pregnancy (threefold), prolonged second stage of labor (threefold), mid-forceps deliveries (tenfold), and increasing birth weight. Of the maneuvers used to deal with shoulder dystocia, strong downward traction on the head was significantly correlated with brachial plexus palsy compared with other individual methods of delivering the shoulders. There was only one case of recurrent shoulder dystocia in 80 women having 93 cephalic vaginal deliveries after their original delivery coded with shoulder dystocia.

CONCLUSION: Shoulder dystocia is not a reliably predictable event in labor. Although the risk of shoulder dystocia is increased with prolonged pregnancy, prolonged second stage of labor, increasing birth weight, and mid-forcepts delivery, the majority of cases occur without these risk factors. Strong downward traction on the head is associated with the greatest degree of neonatal trauma, whereas McRoberts maneuver has the least. The risk of recurrent shoulder dystocia is low.