Predictive Value of Umbilical Artery Half Peak Systolic Velocity Deceleration Time for Adverse Perinatal Outcomes in Gestational Diabetes Mellitus

<b>Objective:</b> To evaluate the predictive value of umbilical artery half peak systolic velocity deceleration time (UA hPSV-DT) for composite adverse perinatal outcomes (CAPO) in pregnancies complicated by gestational diabetes mellitus (GDM). <b>Methods:</b> In this prospective observational study, 120 singleton pregnancies in the third trimester were enrolled: 30 insulin-regulated GDM (IRGDM), 30 diet-regulated GDM (DRGDM), and 60 healthy controls. UA hPSV-DT and standard Doppler indices were measured using a standardized protocol by a single perinatologist. An abnormal UA hPSV-DT was defined as <5th percentile for gestational age. Maternal metabolic parameters, fetal biometry, and neonatal outcomes were recorded. The primary outcome was CAPO, defined as the presence of one or more adverse perinatal events. <b>Results:</b> Median UA hPSV-DT values were significantly lower in IRGDM (171 ms) and DRGDM (184 ms) compared with controls (227 ms) (<i>p</i> = 0.006). Abnormal UA hPSV-DT occurred in 43.3% of GDM cases and was associated with higher estimated fetal weight and abdominal circumference percentiles, increased amniotic fluid, elevated OGTT values, higher HbA1c, and more frequent insulin therapy (<i>p</i> < 0.01 for all). In GDM pregnancies, CAPO occurred in 73.1% of the abnormal UA hPSV-DT group versus 11.8% of the normal group (<i>p</i> < 0.001). ROC analysis identified a cut-off of < 181 ms for predicting CAPO (AUC 0.741, 70.3% sensitivity, 66.7% specificity). <b>Conclusions:</b> UA hPSV-DT is a novel, reproducible Doppler parameter that independently predicts adverse perinatal outcomes in GDM pregnancies, even when conventional UA Doppler indices are normal. Incorporating UA hPSV-DT into routine surveillance may improve risk stratification and guide management to optimize perinatal outcomes.