Impact of Using Abdominal Circumference Independently in the Diagnosis of Fetal Growth Restriction

Area of Science:

• Maternal-Fetal Medicine
• Neonatal Outcomes
• Fetal Growth Assessment

Background:

• Fetal growth restriction (FGR) diagnosis criteria have evolved, with recent guidelines incorporating abdominal circumference (AC) <10th percentile for gestational age (GA) irrespective of estimated fetal weight (EFW).
• This shift necessitates evaluating the diagnostic and predictive performance of different FGR definitions.

Purpose of the Study:

• To compare the predictive accuracy of three FGR definitions for identifying small for gestational age (SGA) neonates.
• To assess the ability of these definitions to predict composite adverse neonatal outcomes (CANO).

Main Methods:

• A secondary analysis of a prospective cohort study involving 1054 women with fetal growth assessments between 26 and 36 weeks GA.
• Comparison of three FGR definitions: EFW <10th percentile, AC <10th percentile, and either EFW or AC <10th percentile.
• Receiver operating characteristic (ROC) curve analysis, specifically the area under the curve (AUC), was used to evaluate discriminatory abilities for predicting SGA and CANO.

Main Results:

• The definition incorporating either EFW or AC <10th percentile demonstrated significantly better prediction of neonatal SGA (AUC=0.74) compared to EFW alone (AUC=0.69) or AC alone (AUC=0.73).
• No significant difference was observed between the three FGR definitions in predicting composite adverse neonatal outcomes (AUCs ranging from 0.50 to 0.51).
• Prevalence rates were: EFW <10th percentile (8.6%), AC <10th percentile (11.6%), and either EFW or AC <10th percentile (12.9%).

Conclusions:

• Incorporating AC <10th percentile alongside EFW enhances the prediction of SGA neonates.
• All evaluated FGR definitions exhibited poor predictive capability for adverse neonatal outcomes.