Timothy P Canavan1, Lyndon M Hill1. 1. Magee Women's Hospital-University of Pittsburgh, Department of Obstetrics, Gynecology, and Reproductive Sciences, Division of Ultrasound, 300 Halket Street, Pittsburgh, PA, 15213.
Abstract
PURPOSE: To compare the estimated fetal weight (EFW), abdominal circumference (AC), and femur length (FL), measured on sonographic (US) examinations at 28-34 weeks of gestation to determine the best predictor of macrosomia at birth. METHODS: We retrospectively evaluated 3,857 consecutive, term, singleton pregnancies. The AC, FL, and EFW were compared with birth weights (BW) of >4,000 g and >4,500 g. RESULTS: There was a statistically significant association between the AC and FL and a BW > 4,000 g or >4,500 g (p < 0.001) whether both or either were in the >90th percentile. There was no statistically significant association between an EFW in the >90th percentile and either BW cutoff. An AC in the >90th percentile alone was the best predictor for macrosomia at birth, with sensitivity, specificity, and positive and negative predictive values of 75%, 74%, 24%, and 96%, respectively (95% confidence intervals [CI]: 73-76%, 73-76%, 23-26%, and 96-97%, respectively), for a BW > 4,000 g. When an AC in the >90th percentile was used to predict a BW > 4,500 g, the sensitivity improved to 88%, but the positive predictive value fell to 5%. Receiver operating characteristic curves comparing the distributions of stratified AC values for BW cutoffs of 4,000 and 4,500 g found the highest areas under the curve of 0.80 (95% CI: 0.77-0.82) and 0.87 (95% CI: 0.83-0.90), respectively. CONCLUSIONS: An AC in the >90th percentile at 28-34 weeks' gestation is the best sonographic predictor of macrosomia at birth.
PURPOSE: To compare the estimated fetal weight (EFW), abdominal circumference (AC), and femur length (FL), measured on sonographic (US) examinations at 28-34 weeks of gestation to determine the best predictor of macrosomia at birth. METHODS: We retrospectively evaluated 3,857 consecutive, term, singleton pregnancies. The AC, FL, and EFW were compared with birth weights (BW) of >4,000 g and >4,500 g. RESULTS: There was a statistically significant association between the AC and FL and a BW > 4,000 g or >4,500 g (p < 0.001) whether both or either were in the >90th percentile. There was no statistically significant association between an EFW in the >90th percentile and either BW cutoff. An AC in the >90th percentile alone was the best predictor for macrosomia at birth, with sensitivity, specificity, and positive and negative predictive values of 75%, 74%, 24%, and 96%, respectively (95% confidence intervals [CI]: 73-76%, 73-76%, 23-26%, and 96-97%, respectively), for a BW > 4,000 g. When an AC in the >90th percentile was used to predict a BW > 4,500 g, the sensitivity improved to 88%, but the positive predictive value fell to 5%. Receiver operating characteristic curves comparing the distributions of stratified AC values for BW cutoffs of 4,000 and 4,500 g found the highest areas under the curve of 0.80 (95% CI: 0.77-0.82) and 0.87 (95% CI: 0.83-0.90), respectively. CONCLUSIONS: An AC in the >90th percentile at 28-34 weeks' gestation is the best sonographic predictor of macrosomia at birth.