Longitudinal Assessment of Abdominal Circumference versus Estimated Fetal Weight in the Detection of Late Fetal Growth Restriction

Abstract

Objectives: To perform a longitudinal assessment comparison between estimated fetal weight (EFW) and abdominal circumference (AC) in the prediction of late fetal growth restriction (FGR) as opposed to small for gestational age (SGA). Patients and Methods: A cohort of unselected singleton pregnancies scanned at 32^±2 and 37^±1 weeks was created. Longitudinal growth assessment by calculating the conditional AC and conditional EFW was performed, and both parameters were compared for their prediction capacity for late FGR and SGA. Conditional standards set an expected size (EFW or AC) given a first measurement performed earlier. A declining growth was defined as a conditional growth of <10th centile. Results: A total of 938 pregnancies were included. As expected, declining growth between 32^±2 and 37^±1 weeks was associated with late FGR and SGA, but the predictive capacity of both conditional AC and conditional EFW was comparably poor, with detection rates of 28% at a 10% rate of false positives for late FGR. Conclusions: Longitudinal assessment of fetal growth during the third trimester has a low predictive capacity for late FGR, with no differences between conditional AC and conditional EFW.