Measurement of Marginal Placental Cord Insertion by Prenatal Ultrasound Was Found Not to Be Predictive of Adverse Perinatal Outcomes

The clinical importance of marginal cord insertion (MCI) is currently controversial. In this study, we examined the association between MCI and adverse perinatal outcomes. We also evaluated the ultrasound-measured distance from the site of placental cord insertion (PCI) to the placental margin (PCI distance) and perinatal outcomes.

This was a retrospective cohort study of MCI and control pregnancies presenting to a single institution between September 2014 and August 2016. Marginal cord insertion was diagnosed on routine anatomy ultrasound scans at 20 weeks' gestation. The primary outcome was fetal intolerance to labor. Secondary outcomes of interest included mode of delivery, gestational age at delivery, Apgar scores at 1 and 5 minutes, birth weight, delivery complications, and neonatal intensive care unit admission. The PCI distance was determined by an ultrasound review. Statistical significance was evaluated by a χ² analysis, descriptive statistics, Wilcoxon tests, and regression models with log-transformed outcomes, the PCI distance, or both as needed.

Of 675 abnormal cord insertion cases, we identified 183 that met inclusion criteria. We found no statistically significant association between MCI and fetal intolerance to labor (odds ratio, 1.24 [95% confidence interval, 0.55-2.80]; P = .71) or secondary outcomes. Furthermore, we found no significant correlation between perinatal outcomes and the PCI distance.

Our study suggests that MCI pregnancies, regardless of the specific PCI distance, might not be at increased risk of adverse perinatal outcomes. This finding questions the need for heightened antepartum surveillance of this patient population.