Objective: To compare the serial ultrasound assessment of abdominal circumference (AC) and fetal weight versus single values of umbilical artery pulsatility index (PI) and the aortic-middle cerebral PI ratio in the identification of fetal growth retardation (FGR).
Methods: Serial AC measurements and estimates of weight were obtained in 104 small fetuses in the third trimester of pregnancy. These serial values (expressed as a change in standard deviation [SD] scores) were compared with the final value of AC and estimated fetal weight (EFW), umbilical artery PI, and the aortic-middle cerebral artery PI ratio (all expressed as SD scores) for their ability to predict a reduced neonatal ponderal index, mid-arm circumference-head circumference (HC) ratio, and skinfold thickness. Receiver-operating characteristic (ROC) curves were derived and the ultrasound measurements evaluated by calculating the areas under the ROC curves.
Results: Serial estimates of fetal weight resulted in a significantly larger area under the ROC curve compared with the final aortic-middle cerebral PI ratio in the prediction of an abnormal mid-arm circumference-HC ratio and compared with the final AC, EFW, and umbilical artery PI in the prediction of all neonatal morphometric indices.
Conclusion: In small fetuses, fetal growth failure as determined by the serial assessment of AC and EFW was superior to the final AC and EFW, umbilical artery PI, and the aortic-middle cerebral PI ratio in the prediction of abnormal neonatal morphometry indicative of FGR.