Association of Umbilical Cord Coiling Index With Pregnancy Outcomes in the Second Trimester: A Prospective Observational Study.

BACKGROUND AND AIMS: The umbilical cord coiling index (UCI) is proposed as a predictor of adverse pregnancy outcomes. However, studies show varying results regarding UCI and prenatal outcomes, particularly between 18 and 24 weeks, indicating a need for further investigation. METHODS: This prospective observational study was conducted at Ayatollah Rouhani Teaching Hospital, Babol, Iran, between 2021 and 2024. Antenatal Umbilical Cord Coiling Index (aUCI) was measured sonographically at 18-24 weeks of gestation, and participants were followed until delivery to record maternal and neonatal outcomes. Multivariable logistic regression was applied to adjust for potential confounders. SPSS version 22 was used for data analysis. RESULTS: Of 422 women initially enrolled, 410 completed follow‑up and were analyzed. The mean antenatal UCI was 0.58 ± 0.14 coils/cm. Based on percentile thresholds, 14.9% were hypocoiled, 73.0% normocoiled, and 12.2% hypercoiled. Perinatal outcomes differed significantly across groups, with higher rates of low birth weight, oligohydramnios, low Apgar score, and preterm labor in abnormal coiling groups compared with normocoiled cords (p < 0.05). Regression analysis showed that hypercoiling was independently associated with premature rupture of membranes (OR = 2.65), low Apgar score (OR = 3.31), oligohydramnios (OR = 5.62), and low birth weight (OR = 3.06). Hypocoiling did not demonstrate significant associations with these outcomes (p > 0.05). CONCLUSION: Hypercoiled cords were associated with an increased risk of LBW, oligohydramnios, low Apgar scores, and PROM. Early UCI evaluation could improve prenatal care by identifying at-risk pregnancies.