The detection of macrosomia at a teaching hospital.

We sought to determine the detection (clinical or sonographic) rate of macrosomic newborns (at least 4000 g) and the peripartum factors among those who were or were not identified accurately. We retrospectively reviewed all deliveries over 1 year and all maternal and neonatal charts of macrosomic newborns delivered during that year. Odds ratio (ORs) and 95% confidence intervals (CIs) were calculated. Over a 12-month period, the rate of macrosomia was 10% (421/4194) and of those, only 11% (95% CI 8 to 14%) were suspected clinically or sonographically. None of the newborns weighing 4500 g or more were recognized before birth (0/57; 95% CI 0 to 6%). The rate of cesarean delivery was significantly higher among newborns correctly identified as macrosomic (58%) versus those missed (36%; OR 2.76, 95% CI 1.46, 5.16). The incidence of newborns weighing in excess of 4000 g is 10%, and approximately 90% of these macrosomic newborns were unsuspected before birth.