Customized estimated fetal weight: a novel antenatal tool to diagnose abnormal fetal growth.

Objective: We sought to apply customized standards to ultrasound-derived estimated fetal weight (EFW), and assess the frequency of abnormal growth when compared to population-based standards. We also evaluated association with adverse perinatal outcomes.

Study Design: This was a historical cohort using prenatal ultrasound examination data at ≥24 weeks over a 1-year period. Ultrasound-derived EFW and growth percentile (population-based EFW [popEFW]) were reported and compared to a customized EFW (custEFW).

Results: In all, 782 women met inclusion criteria. More fetuses were identified as small for gestational age (SGA) (15.1% vs 3.8%; P < .0001) and large for gestational age (LGA) (6.8% vs 1.7%; P < .0001) using custEFW, and adverse perinatal outcomes were more frequent among those identified by the custEFW compared to the popEFW. Both SGA and LGA diagnosed by custEFW were predictive of a neonatal SGA (positive likelihood ratio, 8.64) and LGA (positive likelihood ratio, 15.4).

Conclusion: CustEFW was a better predictor of abnormal birthweight and adverse outcomes compared to traditional popEFW standards.