The outcome of macrosomic infants weighing at least 4500 grams: Los Angeles County + University of Southern California experience.

OBJECTIVE: To describe the maternal and neonatal outcome of macrosomic infants weighing at least 4500 g.

METHODS: Maternal and neonatal records of infants with birth weights of at least 4500 g were identified during 1991. Outcome variables included the mode of delivery and incidence of maternal and perinatal complications.

RESULTS: The study sample consisted of 227 infant and mother pairs. Mean (+/- standard deviation) birth weight was 4706 +/- 219 g. A trial of labor was allowed in 192 women, and elective cesarean delivery was performed in 35 patients. The overall cesarean rate, including elective cesarean delivery and failed trial of labor, was 30.8% (70 of 227). Of those undergoing a trial of labor, 82% (157) delivered vaginally. Shoulder dystocia occurred 29 times, for an incidence of 18.5% in vaginal deliveries for macrosomia. There were seven cases each of Erb palsy and clavicular fracture, and one humeral fracture. By 2 months of age, all affected infants were without permanent sequelae. There was no birth asphyxia or perinatal mortality related to delivery for macrosomia. Maternal complications included increased risk of lacerations requiring repair (especially third- or fourth-degree lacerations) when vaginal delivery was complicated by shoulder dystocia (relative risk [RR] 5.4, 95% confidence interval [CI] 3.1-9.4). There was no statistically significant difference with respect to hemorrhage or hospital stay for women who had a vaginal delivery (with or without shoulder dystocia) compared with women who had a cesarean delivery. However, infectious morbidity increased significantly in those patients who underwent a cesarean after a trial of labor compared with women who had a vaginal delivery (RR 7.1, 95% CI 3.9-13.1) or elective cesarean birth (RR 5.4, 95% CI 3.1-9.4). Ninety-one percent of patients undergoing elective cesarean delivery had no complications.

CONCLUSION: Vaginal delivery is a reasonable alternative to elective cesarean for infants with estimated birth weights of at least 4500 g, and a trial of labor can be offered.