Growth Velocity and Sonographic Estimation of Birthweight Among Low-Risk Pregnancies

Objective: To examine whether addition of fetal growth velocities, based on serial scans, compared to estimated fetal weight (EFW) alone, improves prediction accuracy of birthweight (BW). Study Design: From the prospective NICHD Fetal Growth Studies–Singletons (2009-2013) that recruited women at low-risk for aberrant fetal growth, we included 2,397 participants with two to five ultrasounds between 15-41 weeks. Fetal growth velocity (V) was calculated between successive visits. Linear regression estimated relationship between EFW and BW: Non-V model, absent all growth velocities, included EFW at visit 5, interval from visit 5 to delivery, their cubic polynomials, and delivery gestational age (GA); All-V model added all available velocities between research visits (i.e., V2+V3+V4+V5) to the Non-V model; Single-V model added only the velocity between visit 4 and 5. Results: Non-V performed the worst, with the highest mean absolute error of 197 g and lowest R2, 0.63. The two best performing models were All-V and Single-V, with the lowest mean absolute error (192 g for both), highest R2 of 0.65 (for both), and greatest proportion of predicted BWs within 10% of actual BW (84.7% for both). Conclusion: Integrating fetal growth velocities into BW estimating formulas improved BW prediction accuracy which has potential to guide clinical intervention decisions that rely on EFW.

Publikationsverlauf

Eingereicht: 22. Mai 2025

Angenommen nach Revision: 05. August 2025

Accepted Manuscript online:
07. August 2025