Umbilical Coiling Index, Doppler Parameters, and Cord Blood Gas Analysis: Lack of Correlation in Uncomplicated Term Pregnancies

<b>Background/Objectives</b>: In this study, we aimed to evaluate whether neonatal ischemia-modified albumin (IMA) and umbilical venous cord blood gas parameters are associated with antenatal markers of fetal well-being, including the umbilical coiling index (UCI) and umbilical artery (UA) and middle cerebral artery (MCA) Doppler indices. <b>Methods</b>: For this prospective observational study, sixty-five low-risk term pregnancies (≥37 weeks) were included. Prenatal ultrasound was used to measure the UCI and UA/MCA Doppler indices. At delivery, umbilical venous cord blood gas and serum IMA analyses were performed. Maternal and neonatal data (birth weight, 5 min Apgar score, NICU admission, sex, and delivery mode) were recorded, and correlations and group comparisons were performed (<i>p</i> < 0.05). <b>Results</b>: The UCI ranged from 0.210 to 0.471 coil/cm (mean 0.337). The UA and MCA Doppler indices were within the reference ranges. The UCI showed no significant correlation with umbilical venous blood gas values, IMA, UA/MCA Doppler indices, gestational age/weeks, or 5 min Apgar score. The UA S/D ratio and UA resistive index (RI) were negatively correlated with birth weight (<i>p</i> < 0.05). Umbilical venous pH was positively correlated with the 5 min Apgar score, whereas venous pCO₂ was negatively correlated with the 5 min Apgar score (both <i>p</i> < 0.05). Newborns with venous pH < 7.32 had higher cesarean delivery rates and higher rooming-in rates. Newborns admitted to the NICU had higher mean UA systolic velocity/diastolic velocity (S/D) and UA pulsatility index (PI) and lower venous pH. <b>Conclusions</b>: In low-risk term pregnancies, the UCI was not associated with cord blood gas parameters, IMA, or UA/MCA Doppler indices. These results suggest that the UCI may have limited clinical utility as a predictor of early neonatal acidosis or oxidative stress in a strictly low-risk population.