The objective of this paper is to identify maternal risk factors for abnormal vascular coiling of the umbilical cord. The umbilical cords of 657 neonates were examined and the coiling index determined by dividing the total number of complete vascular coils by the length of the cord in cm. Obstetrical history, delivery data, and neonatal outcome were also evaluated. The frequency distribution of umbilical coiling index was normal (10 th and 90th percentile and mean +/- SD = 0.17, 0.37, and 0.26 +/- 0.09 coils/cm, respectively). Maternal risk factors for abnormal vascular coiling were extremes of age for hyper-coiling, obesity, gestational diabetes mellitus, and preeclampsia for non-coiling. Hyper-coiled and non-coiled cords were significantly associated with adverse perinatal outcome (p < 0.001) and cesarean delivery (p < 0.0001). Neonates whose mothers are old or young, obese, diabetic, or have preeclampsia are likely to have hyper-coiled or non-coiled umbilical blood vessels.