P29.05: Placental cord insertion site and adverse pregnancy outcome in twin pregnancy

Abstract

Abnormal umbilical cord insertion has been associated with unequal sharing of the placental vasculature between twins. A higher prevalence has been reported in pregnancies complicated by selective growth restriction (sFGR), birth weight discordance (BWD). We aimed to investigate the association between cord insertion site and adverse pregnancy outcomes in twin pregnancies. A single-centre cohort study of twin pregnancies that had placental histology. Higher-order multiples, major fetal anomaly, aneuploidy and MCMA pregnancies were excluded. Cord insertion site was categorised into 3 groups: marginal (attachment <2cm to the placental margin), velamentous (attached to the membrane before reaching the placenta with vessels traversing the membranes), normal. Chorionicity, placental weight, number of cord vessels, examination of the membranes, ultrasound findings, maternal characteristics and pregnancy outcome were collected. 546 pregnancies were eligible; 497 (146 monochorionic; 351 dichorionic) were included in the analysis. Significant differences were found between the normal and abnormal cord insertion groups with regards to BWD (P=0.001), BWD>25% (P=0.001), and absolute Z-score differences (P=0.020). Velamentous, but not marginal, cord insertion was significantly associated with sFGR (OR 8.51,95%CI 2.09-34.58;P=0.03) and BWD>25% (OR 11.88,95%CI 3.54-39.79;P=0.04). In MCDA, but not DCDA pregnancies, the rate of composite adverse outcome was higher in those with abnormal cord insertion (70.0% vs 53.0%, p=0.04). Selective fetal growth restriction and birthweight discordance are more common in twin pregnancies with abnormal cord insertion. MCDA twins with velamentous cord insertion are at increased risk of sFGR, and composite adverse pregnancy outcome.