Insights into the Hepatic Arterial Buffer Response in Late-Onset FGR.

Objective: To evaluate hepatic artery Doppler parameters in fetuses with fetal growth restriction (FGR) and to investigate their relationship with composite adverse neonatal outcomes (CANO). Methods: This prospective cohort study included 108 pregnancies (54 FGR; 54 appropriate-for-gestational-age controls) between 34 and 37 weeks' gestation. Hepatic artery (HA), umbilical artery (UA), middle cerebral artery (MCA), and uterine artery Doppler indices were recorded. Logistic regression and ROC analyses were used to determine predictors of FGR and CANO. Results: HA pulsatility index (PI), systolic/diastolic ratio, and peak systolic velocity (PSV) were significantly higher in FGR fetuses (p < 0.05). In multivariate regression, HA-PI remained independently associated with FGR (aOR 1.74, 95% CI 1.07-2.87, p = 0.025). For predicting CANO, HA-PSV was the only independent predictor (aOR 1.05, 95% CI 1.00-1.10, p = 0.020). ROC analysis demonstrated moderate discriminative ability for HA-PI (AUC 0.681) and HA-PSV (AUC 0.703). Conclusions: Increased HA-PSV in FGR reflects activation of the hepatic arterial buffer response as an adaptive mechanism to maintain hepatic perfusion under hypoxic stress, whereas elevated HA-PI may represent evolving microvascular resistance. Hepatic artery Doppler evaluation may serve as a complementary tool for assessing fetal well-being and identifying fetuses at risk for adverse neonatal outcomes, particularly in late-onset FGR.