Associations Between Velamentous or Marginal Cord Insertion and Risk of Adverse Perinatal Outcomes in Twin Pregnancies: A Retrospective Cohort Study

Abstract

Abstract Background velamentous cord insertion (VCI) and marginal cord insertion (MCI) are well-known risk factors for adverse perinatal outcomes in singleton pregnancies. However, the potential links between VCI or MCI and perinatal outcomes in twin pregnancies have yet to be systematically evaluated. This study aimed to investigate the relationships between VCI or MCI and perinatal outcomes, neonatal outcomes in twin pregnancies. Methods This was a retrospective single-center cohort study that included women with twin pregnancies and gave birth in a tertiary hospital in Southwest, China between January 2017 and December 2022. VCI and MCI were identified by abdominal ultrasound and checked after placenta delivery. Logistic regression models, multinomial logit regression models and generalized estimation equation models were used to evaluated the association between VCI or MCI and perinatal outcomes. Results 3682 twin pregnancies were included, 100 (2.7%) pregnancies with VCI and 149 (4.0%) pregnancies with MCI. Compared to pregnancies with normal cord insertion, pregnancies with VCI were associated with an increased risk of preterm delivery 32–34 weeks both in monochorionic twins (aRRR 2.94, 95% CI 1.03–8.39) and dichorionic twins (aRRR 2.55, 95% CI 1.19–5.46), while pregnancies with MCI were not associated with preterm delivery. Pregnancies with VCI were associated with higher incidence of placental previa (aOR 6.36, 95% CI 1.92–21.04) in monochorionic twins and placental accreta in dichorionic twins (aOR 1.85, 95% CI 1.06–3.23). Pregnancies with MCI were associated with increased risk of preeclampsia (aOR 3.07, 95% CI 1.49–6.32), intertwin birthweight discordance ≥ 20% (aOR 2.40, 95% CI 1.08–5.60) and selective fetal growth restriction (aOR 2.46, 95% CI 1.08–5.60) in monochorionic twins and small-for-gestational age neonates (aOR 1.97, 95% CI 1.24–3.14) in dichorionic twins. Conclusions Twin pregnancies with VCI were associated with an increased risk of preterm delivery irrespective of chorionicity, whereas twin pregnancies with MCI were associated with an increased risk of preeclampsia, significant intertwin birthweight discordance in monochorionic twins and small-for-gestational age neonates in dichorionic twins.