To evaluate umbilical cord coiling in pregnancies with adverse outcome.Umbilical cords and hospital records of 565 consecutive cases with an indication for histological examination of the placenta were studied. The umbilical coiling index (UCI) was determined as the number of complete coils divided by the length of the cord in centimeters, by an observer blinded for pregnancy outcome. Data on obstetric history and pregnancy outcome of each case were obtained from the hospital records. We calculated odds ratios and their 95% confidence interval to evaluate the strength of associations between pregnancy outcome and abnormal cord coiling.Fetal death (OR 4.09, 95% CI 2.22-7.55), chorioamnionitis (OR 1.77, 95% CI 1.09-2.88), fetal structural or chromosomal abnormalities (OR 1.78, 95% CI 1.08-2.95), and lower Apgar score at 5 min (p=0.03) were associated with undercoiling (UCI below the 10th percentile, using reference values from uncomplicated pregnancies). Fetal death (OR 3.74, 95% CI 1.89-7.40), iatrogenic preterm delivery (OR 1.91, 95% CI 1.04-3.49), umbilical arterial pH<7.05 (OR 3.63, 95% CI 1.44-9.17), fetal structural or chromosomal abnormalities (OR 1.79, 95% CI 1.01-3.16), thrombosis in fetal placental vessels (OR 2.64, 95% CI 1.37-5.06), chronic fetal hypoxia/ischemia (OR 1.82, 95% CI 1.09-3.05), and lower weight for gestational age (p=0.01) were associated with overcoiling (UCI above the 90th percentile).Our findings confirm that adverse perinatal outcome is associated with both undercoiling and overcoiling of the umbilical cord.