Objective: To estimate the relation between undercoiling and overcoiling of the umbilical cord and adverse pregnancy outcome.
Methods: Umbilical cords and hospital records of 885 patients were studied in a cross-sectional study design. The umbilical coiling index was determined as the number of complete coils divided by the length of the cord in centimeters, blinded for pregnancy outcome. Obstetric history and pregnancy outcome of each patient were obtained from hospital records, blinded for the umbilical coiling index. Odds ratios and their 95% confidence intervals were calculated to evaluate associations between undercoiling and overcoiling and adverse pregnancy outcome, using multiple logistic regression.
Results: Undercoiling (umbilical coiling index below the 10th percentile, using references values from uncomplicated pregnancies) was associated with fetal death (odds ratio [OR] 3.35, 95% confidence interval [CI] 1.48-7.63), spontaneous preterm delivery (OR 2.16, 95% CI 1.34-3.48), trisomies (OR 5.79, 95% CI 2.07-16.24), low Apgar score at 5 minutes (OR 3.14, 95% CI 1.47-6.70), velamentous cord insertion (OR 3.00, 95% CI 1.16-7.76), single umbilical artery (OR 3.68, 95% CI 1.26-10.79), and dextral coiling (OR 1.80, 95% CI 1.02-3.17). Overcoiling (umbilical coiling index above the 90th percentile) was associated with asphyxia (OR 4.16, 95% CI 1.30-13.36), umbilical arterial pH < 7.05 (OR 2.91, 95% CI 1.05-8.09), small for gestational age infants (OR 2.10, 95% CI 1.01-4.36), trisomies (OR 9.26, 95% CI 2.84-30.2), single umbilical artery (OR 8.25, 95% CI 2.60-26.12), and sinistral coiling (OR 4.30, 95% CI 1.52-12.2).
Conclusion: Undercoiling and overcoiling of the umbilical cord are associated with increased risk for adverse perinatal outcome.