Obstetric and neonatal implications of ultrasonographically diagnosed marginal cord insertion: a retrospective analysis.

Abstract

Background: Marginal cord insertion (MCI) is an anatomical variation hypothesized to cause suboptimal placentation, but its independent impact on perinatal outcomes remains controversial.

Objective: This study aimed to evaluate the independent impact of ultrasonographically diagnosed MCI on obstetric and neonatal outcomes.

Methods: This retrospective case-control study conducted at a tertiary center between January 2022 and January 2025 screened 3,247 pregnancies. Thirty-six cases diagnosed with MCI were initially matched with 108 central cord insertion controls (1:3 ratio) for baseline comparisons. After excluding four MCI cases due to major fetal anomalies or demise, the final analysis included 32 MCI cases and 108 controls. Baseline characteristics, gestational comorbidities, and neonatal outcomes were compared. Multivariable logistic regression adjusted for maternal age and BMI.

Results: The incidence of MCI was 1.1%. In univariate analysis, the MCI group had significantly higher rates of preterm delivery (28.1% vs. 9.3%; p = 0.015), lower median birth weight (3087.5 g vs. 3300 g; p = 0.038), and lower 1-minute and 5-minute Apgar scores (p = 0.016 and p = 0.015, respectively) compared to controls. In the multivariable model, MCI was associated with increased odds of preterm birth (aOR: 6.36; 95% CI: 1.73-23.41; p = 0.005). However, associations with low birth weight (aOR: 3.49; p = 0.331) and low Apgar scores did not maintain statistical significance in the adjusted model.

Conclusion: MCI is associated with increased odds of preterm birth in our cohort. While neonatal morbidity appears to be primarily mediated by shortened gestation, further large-scale studies are needed to determine whether standardized antenatal surveillance can improve outcomes.