The length of umbilical cords was studied in 536 term deliveries to test the hypothesis that a short or long umbilical cord is more frequently associated with certain intrapartum complications. The mean umbilical cord length was 55 cm (range, 14 to 129 cm). A short cord was defined as 35 cm or less (lower sixth percentile). Umbilical cord accidents were most frequent in the presence of a long cord (20 of 32 cases, 62%). Inadequate fetal descent was significantly more common when a long cord or an excessively short cord (25 cm or less, lower first percentile) was found. Fetal heart rate (FHR) abnormalities that primarily reflected cord compression patterns were significantly more frequent in the presence of a short (17 of 27 cases, 63%) or a long cord (28 of 32 cases, 87%), as compared with a normal length cord (145 of 393 cases, 37%). The measurement of umbilical cord length requires minimal effort, no expense, and may explain certain intrapartum FHR abnormalities or an arrest of fetal descent.