Incidence of persistent birth injury in macrosomic infants: association with mode of delivery.

Abstract

Our purpose was to determine the incidence of birth injury in a cohort of macrosomic infants (birth weight >4000 gm) and analyze the association between persistent injury and delivery method. Deliveries of 2924 macrosomic infants were reviewed. Outcomes were compared with those of 16,711 infants with birth weights between 3000 and 3999 gm. Macrosomic infants had a sixfold increase in significant injury relative to controls (relative risk 6.7,95% confidence interval 6.5 to 6.9). Risk of trauma correlated with delivery mode: forceps were associated with a fourfold risk of clinically persistent findings compared with spontaneous vaginal delivery or cesarean section. However, the overall incidence of persistent cases remained low (0.3%); a policy of elective cesarean section for macrosomia would necessitate 148 to 258 cesarean sections to prevent a single persistent injury. Avoidance of operative vaginal delivery would require 50 to 99 cesarean sections per injury prevented. These findings support a trial of labor and judicious operative vaginal delivery for macrosomic infants.