Role of Umbilical Cord Diameter in Detection of Gestational Age in pregnant women

Background: Accurate estimation of gestational age (GA) is important for optimal prenatal care. While traditional biometric parameters such as biparietal diameter (BPD), femur length (FL), and head circumference (HC) are widely used, umbilical cord diameter (UCD) has emerged as a promising additional marker. Aim: to evaluate the accuracy of UCD in determining GA and its association with fetal weight (FW) and APGAR scores. Methods: This prospective cohort study included 350 pregnant women in their second and third trimesters attending Al-Azhar University Hospitals between August 2023 and March 2025. Standard ultrasound parameters (BPD, FL, HC, abdominal circumference, amniotic fluid index) and UCD were measured. GA was determined by clinical and sonographic methods, and neonatal outcomes (FW, APGAR score at 5 minutes) were recorded after delivery. Results: UCD increased significantly with advancing GA, from 1.2 ± 0.16 cm in the early second trimester to 1.5 ± 0.13 cm in the third trimester (F = 564.6, p < 0.001). A strong positive correlation was observed between UCD and GA (r = 0.822, p < 0.001), with an approximate increase of 0.02 cm per gestational week. UCD showed a moderate positive correlation with FW (≈ 552 g increase per 1 mm UCD; p < 0.001) and a weak positive correlation with APGAR scores (0.58-unit increase per 1 mm UCD; p < 0.05). Other fetal biometric parameters demonstrated very strong correlations with GA, while AFI correlated negatively. Conclusion: UCD is a reliable parameter for estimating GA, correlating strongly with fetal growth and moderately with neonatal outcomes.