Prevalence, Risk Factors and Outcomes of Velamentous and Marginal Cord Insertions: A Population-Based Study

Objectives: To determine the prevalence of, and risk factors for anomalous insertions of the umbilical cord, and the risk for adverse outcomes of these pregnancies. Design: Population-based registry study. Setting: Medical Birth Registry of Norway 1999–2009. Population: All births (gestational age.16 weeks to,45 weeks) in Norway (623,478 singletons and 11,263 pairs of twins). Methods: Descriptive statistics and odds ratios (ORs) for risk factors and adverse outcomes based on logistic regressions adjusted for confounders. Main outcome measures: Velamentous or marginal cord insertion. Abruption of the placenta, placenta praevia, pre-eclampsia, preterm birth, operative delivery, low Apgar score, transferral to neonatal intensive care unit (NICU), malformations, birthweight, and perinatal death. Results: The prevalence of abnormal cord insertion was 7.8 % (1.5 % velamentous, 6.3 % marginal) in singleton pregnancies and 16.9 % (6 % velamentous, 10.9 % marginal) in twins. The two conditions shared risk factors; twin gestation and pregnancies conceived with the aid of assisted reproductive technology were the most important, while bleeding in pregnancy, advanced maternal age, maternal chronic disease, female foetus and previous pregnancy with anomalous cor