RESUMO
OBJECTIVE: To provide reference values for the umbilical coiling index in uncomplicated pregnancy. METHODS: Umbilical cords were collected from livebom singleton infants born after uncomplicated pregnancies. The umbilical coiling index (UCI) was calculated as the number of coils divided by the cord length in centimeters. The mean value (SD) for the UCI was calculated, and possible correlations of the UCI with maternal age, parity, gestational age at delivery, mode of delivery, sex and birth weight of the infant were examined. RESULTS: A total of 122 umbilical cords were included. The frequency distribution of the UCI was skewed to the right. The mean (SD) UCI was 0.17 (0.009) coils/cm. There were no significant correlations of the UCI with maternal age, parity, gestational age at delivery, mode of delivery, sex or birth weight of the infant. CONCLUSIONS: This is the first study to determine the UCI in a group exclusively consisting of uncomplicated pregnancies. The mean value that we found for the UCI may serve as the standard reference, allowing proper interpretation of umbilical coiling in complicated pregnancy.