The risk of shoulder dystocia related permanent fetal injury in relation to birth weight.

OBJECTIVE: To examine birth weight related risks of fetal injury in connection with shoulder dystocia.

STUDY DESIGN: The investigation was based on a retrospective analysis of 316 fetal neurological injuries associated with deliveries complicated by arrest of the shoulders that occurred across the United States.

RESULTS: The study revealed that the distribution of birthweights for the high risk shoulder dystocia population differs from the standard birthweight distribution. The relative difference per birthweight interval is used to adjust an assumed 1:1000 baseline risk of injury due to shoulder dystocia following vaginal deliveries. These adjusted risks show a need to consider new thresholds for elective cesarean delivery.

CONCLUSIONS: Current North American and British guidelines, that set 5000 g as minimum estimated fetal weight limit for elective cesarean section in non-diabetic and 4500 g for diabetic gravidas, may expose some macrosomic fetuses to a high risk of permanent neurological damage. The authors present the opinion that the mother, having been informed of the risks of vaginal versus abdominal delivery, should be allowed to play an active role in the critical management decisions.