Umbilical Cord Insertion Anomalies and Pregnancy Outcomes

Umbilical cord insertion anomalies occur when the cord attaches eccentrically to the placental disc rather than centrally. The two most common forms are marginal insertion, where the cord inserts at or within 2 cm of the placental edge, and velamentous insertion, in which vessels traverse the membranes before joining the placenta. These abnormalities have been linked to adverse outcomes including preterm birth, foetal growth restriction, low birthweight, emergency caesarean delivery and, in severe cases, perinatal mortality. The anomalous vascular course in velamentous insertion renders the foetus vulnerable to vessel compression and rupture, particularly in the presence of vasa praevia. Marginal insertion, though generally less severe, has been associated with reduced placental perfusion and an elevated risk of small for gestational age infants. Risk factors span assisted reproductive technologies, twin gestation, advanced maternal age, smoking and previous obstetric history. Prenatal sonographic assessment of insertion site during routine second-trimester scans has become increasingly advocated to inform pregnancy management, optimise surveillance and reduce emergency interventions. Emerging work further explores the role of anomalous insertion in umbilical cord cyst formation, placental haemangiomas and long-term neurodevelopmental outcomes. Collectively, research underscores the global importance of early detection and multidisciplinary care in pregnancies complicated by insertion anomalies.

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Umbilical Cord Insertion Anomalies and Pregnancy Outcomes publication trend

The graph below shows the total number of articles in umbilical cord insertion anomalies and pregnancy outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

Velamentous cord insertion: insertion of umbilical vessels into the membranes rather than the placental disc, leaving vessels unprotected by Wharton’s jelly.

Marginal cord insertion: attachment of the cord at or near the placental margin, within 2 cm of the edge.

Vasa praevia: condition where foetal vessels run across the internal cervical os, at high risk of rupture.

Small for gestational age (SGA): birthweight below the 10th percentile for gestational age.

Twin-to-twin transfusion syndrome: vascular anastomoses in monochorionic twins leading to blood flow imbalance between foetuses.

References

1. Abnormal placental cord insertion and adverse pregnancy outcomes: a systematic review and meta-analysis. Systematic Reviews (2017).
2. Assisted Reproductive Technique and Abnormal Cord Insertion: A Systematic Review and Meta-Analysis. Biomedicines (2022).
3. Prevalence, Risk Factors and Outcomes of Velamentous and Marginal Cord Insertions: A Population-Based Study of 634,741 Pregnancies. PLOS ONE (2013).
4. Velamentous cord insertion: results from a rapid review of incidence, risk factors, adverse outcomes and screening. Systematic Reviews (2020).
5. Marginal cord insertion among singleton births at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia. BMC Pregnancy and Childbirth (2021).
6. Prevalence, Risk Factors, and Perinatal Outcomes of Velamentous Umbilical Cord Insertion in Twin Pregnancies: A Single-Center Retrospective Study. Journal of Clinical Medicine (2024).