Umbilical venous flow and maternal hemodynamics as predictors of impaired fetal growth in gestational diabetes: a prospective study

This study aims to evaluate the association between maternal cardiovascular function, umbilical vein blood flow (UV-Q), and impaired fetal growth in pregnancies complicated by gestational diabetes mellitus (GDM). In this prospective observational study, 84 singleton pregnancies complicated by GDM between 28 and 32 weeks of gestation were enrolled. All participants underwent a standardized maternal hemodynamic assessment using USCOM device and fetal ultrasound including Doppler-based measurement of UV-Q. Impaired fetal growth was defined as either small for gestational age (SGA, birthweight <10th centile) or a ≥40 centile drop between estimated fetal weight (EFW) at enrolment and actual birthweight centile ("DROP"). Predictive performance was assessed using ROC analysis and multivariate logistic regression. Fetuses with impaired growth (n=24) had significantly lower UV-Q centiles (median 29.50 vs. 50.00, p=0.04), higher maternal systemic vascular resistance (SVR) (1,004.50 vs. 915.00 dyn s cm-5, p<0.01), lower cardiac output (CO) (6.5 vs. 7.2 L/min, p=0.03), and reduced oxygen delivery (DO2) (1,021.22 vs. 1,131.06 mL/min, p<0.01) compared to those with normal growth. Multivariate analysis identified UV-Q centile ≤24, SVR>916 dyn s cm-5, and DO2≤1,061.4 as independent predictors of impaired growth (AUC up to 0.78). These associations remained significant after adjusting for EFW at enrolment. In pregnancies complicated by GDM, impaired fetal growth may reflect placental dysfunction and maternal cardiovascular maladaptation. Maternal hemodynamic parameters and UV-Q may enhance fetal growth surveillance, particularly when incorporating longitudinal metrics such as DROP. These findings suggest a potential role for integrating maternal-fetal hemodynamics into standard care to identify "hidden"growth restriction phenotypes in GDM pregnancies.