25 YEARS LATER - MUST MACROSOMIC FETUSES BE DELIVERED BY ROUTINE CESAREAN SECTION? A CROSS-SECTIONAL STUDY.

To determine the appropriateness of guidelines recommending routine Cesarean section (CS) for the delivery of macrosomic fetuses weighing ?4500 grams.

This was a cross-sectional study of trends and outcomes of macrosomic deliveries at a single, tertiary hospital over a 35 yearperiod (1980 to 2015). A previous review of macrosomic deliveries suggested safety of vaginal delivery in this population locally. Outcomes from that ‘Early Group’ (1980-1989) were then compared to a ‘Late Group’ (2006-2015). Delivery records and hospital charts for all newborns weighing ?4500 grams at birth were reviewed to determine the prevalence of macrosomia as well as mode of delivery and other maternal covariates in order to compare outcomes between groups.

The rate of macrosomia has been stable over the past 35years (2.3% Early Group vs 2.7% Late Group, p=0.4). Most macrosomic fetuses were successfully delivered vaginally, although the rate of emergency intrapartum CS has increased (18% Early Group vs 27% Late Group, p<0.0001). The prevalence of shoulder dystocia has also remained stable. There were no intrapartum fetal deaths nor long-term injuries as a result of mechanical complications at vaginal delivery.

While some professional guidelines have recommended that all macrosomic fetuses be delivered by routine CS, this has not been our local practice and to date, no macrosomic baby at our centre has died or been permanently injured as a result of intrapartum complications of vaginal delivery. However, the emergency CS rate in this population has increased from 18 to 27% and warrants further study.