Predicting macrosomia

Objective. The purpose of this study was to evaluate the prediction of fetal macrosomia based on ultrasound estimates of fetal weight and amniotic fluid volume combined with clinical risk factors. Methods. A retrospective cohort study of women undergoing indicated obstetric ultrasound examinations within 7 days of delivery was conducted. Results. A total of 3115 women gave birth within 7 days of ultrasound examinations that included an estimated fetal weight (EFW) and an amniotic fluid index (AFI). Clinical risk factors were associated with an 8% positive predictive value for a birth weight of 4000 g or higher. Adding an ultrasound EFW of 4000 g or higher increased the positive predictive value to 62%. Adding an AFI of 20 cm or higher to the clinical risk factors and the ultrasound EFW further increased the positive predictive value to 71%. Conclusions. An ultrasound EFW of 4000 g or higher within 1 week of delivery combined with clinical risk factors and an increased AFI is associated with macrosomia at birth in 71% of cases.