(1191) Growth Velocity vs Doppler Flow: Rethinking Surveillance in Growth-Restricted Fetuses

Objective:
Current delivery recommendations for growth-restricted fetuses rely heavily on umbilical artery (UA) Doppler indices, which are well validated in cases with absent or reversed end-diastolic flow. However, management of fetuses with preserved forward flow remains largely guided by expert opinion. Growth velocity may be an important tool in growth restricted fetuses. We aimed to compare the predictive performance of growth velocity with UA systolic/diastolic (S/D) ratio in identifying adverse outcomes. 

Study Design:
This retrospective cohort study included pregnant patients aged 18–45 who delivered between 2012–2022. Exclusions included congenital anomalies and multiple gestations. Growth velocity was calculated as the weekly change in estimated fetal weight percentile between 26–32 and 32–36 weeks. The final UA S/D ratio was used. The primary outcome was a composite of neonatal morbidity and severe adverse perinatal events. Secondary outcomes included neonatal morbidity events, severe adverse perinatal events, neonatal intensive care unit admission, and respiratory complications. Univariate logistic regression and receiver operator curve analyses were used. 

Results:
Of 324 patients with growth velocity data, 189 had UA Doppler data. Among them, 29 (15.3%) had an S/D ratio >95th percentile; none had absent or reversed end-diastolic flow. Baseline characteristics were similar across groups. There was no significant correlation between growth velocity and S/D ratio (r = -0.05, p = 0.50). The area under the curve (AUC) for the S/D ratio in predicting the primary outcome was 0.48 (95% CI: 0.39-0.57), while growth velocity showed improved discrimination with an AUC of 0.61 (95% CI: 0.53-0.70) for growth velocity only and 0.62 (95% CI: 0.55–0.68) for the full cohort; see Figure 1. A similar pattern was observed across secondary outcomes.

Conclusion:
In growth-restricted fetuses with forward UA flow, growth velocity appears to outperform the UA S/D ratio in predicting adverse outcomes. These findings support growth velocity as a valuable tool to enhance fetal risk stratification and guide delivery decisions.