Objective: The purpose of this study was to evaluate the antenatal umbilical cord coiling index obtained during the fetal anatomic survey in the second trimester as a predictor of adverse pregnancy outcome. Study design: Four hundred twenty-five consecutive women who had a fetal anatomic survey between 18 to 23 weeks of gestation were evaluated for umbilical cord coiling. The antenatal umbilical cord coiling index was calculated as a reciprocal value of the distance between a pair of coils (antenatal umbilical cord coiling index = 1/distance in cm) and was correlated with the following adverse pregnancy outcomes: (1) small for gestational age, (2) mode of delivery, (3) presence of meconium-stained amniotic fluid, (4) presence of nonreassuring fetal status in labor, and (5) Apgar scores at 1 and 5 minutes. Results: A total of 294 patients had adequate ultrasound images and all antenatal and labor data to meet the study inclusion criteria. Abnormal coiling was associated significantly with small for gestational age neonates at birth (P = .043) and nonreassuring fetal status in labor (P = .007). Nine of 58 neonates (15.5% ) with abnormal umbilical coiling were small for gestational age infants compared with 15 of 236 small for gestational age neonates (6.4% ) who had normal cord coiling. A nonreassuring fetal status in labor was observed in 25.7% of fetuses (15/58 fetuses) with abnormal umbilical coiling compared with 11.0% of fetuses (26/236 fetuses) with normal cord coiling. In contrast, no statistical difference for Apgar scores at 1 and 5 minutes or higher prevalence of interventional deliveries and meconium-stained amniotic fluid in labor between the groups with normal and abnormal umbilical cord coiling was observed. Conclusion: Abnormal umbilical cord coiling that is detected at the fetal ultrasound anatomic survey in the second trimester is associated with a higher prevalence of small for gestational age neonates and nonreassuring fetal status in labor. This observation can be used potentially as a predictor of adverse antenatal or perinatal events in future studies. Objective: The purpose of this study was to evaluate the antenatal umbilical cord coiling index obtained during the fetal anatomic survey in the second trimester as a predictor of adverse pregnancy outcome. Study design: Four hundred twenty-five consecutive women who had a fetal anatomic survey between 18 to 23 weeks of gestation were evaluated for umbilical cord coiling. The antenatal umbilical cord coiling index was calculated as a reciprocal value of the distance between a pair of coils (antenatal umbilical cord coiling index = 1 / distance in cm) and was correlated with the following adverse pregnancy outcomes: (1) small for gestational age, (2) mode of delivery, (3) presence of meconium-stained amniotic fluid, (4) presence of nonreassuring fetal status in labor, and at 1 and 5 minutes. Results: A total of 294 patients had adequate ultrasound images and all antenatal and labor data to meet the study inclusion criteria. Abnormal coiling was associated significantly wi Th small for gestational age neonates at birth (P = .043) and nonreassuring fetal status in labor (P = .007). Nine of 58 neonates (15.5%) with abnormal umbilical coiling were small for gestational age infants compared with 15 of 236 small for gestational age neonates (6.4%) who had normal cord coiling. A nonreassuring fetal status in labor was observed in 25.7% of fetuses (15/58 fetuses) with abnormal umbilical coiling compared with 11.0% of fetuses (26/236 fetuses) with normal cord coiling. In contrast, no statistical difference for Apgar scores at 1 and 5 minutes or higher prevalence of interventional deliveries and meconium-stained amniotic fluid in labor between the groups with normal and abnormal umbilical cord coiling was observed. Conclusion: Abnormal umbilical cord coiling that is detected at the fetal ultrasound anatomic survey in the second trimester is associated with a higher prevalence of small for gestational age neonates and nonreassuring fetal status in labor. This observation can be used potentially as a predictor of adverse antenatal or perinatal events in future studies.