A systematic review and meta-analysis of velamentous cord insertion among singleton pregnancies and the risk of preterm delivery

Background: Observational studies have reported varying results about the association of velamentous cord insertion (VCI) with adverse pregnancy outcomes. Objectives: To evaluate the risk of preterm delivery among singleton pregnancies complicated by VCI. Search strategy: Various databases were searched for English-language articles published up to February, 28, 2017, using keywords including VCI; abnormal placentation; abnormal cord insertions; adverse perinatal outcomes; and preterm birth. Outcome measures included preterm delivery; pre-eclampsia; cesarean delivery; fetal demise in utero (FDIU); and small for gestational age (SGA). Selection criteria: Only studies involving VCI were included in the meta-analysis. Data collection and analysis: Analyses were performed using RevMan version 5.3.5 (The Nordic Cochrane Centre, Copenhagen, Denmark). Main results: There were six studies included in the analysis. The VCI and control groups comprised 16 295 and 1 366 485 women, respectively. An increased incidence of preterm delivery was found for the VCI group compared with the control group (11.8% vs 7.0%; adjusted odds ratio [aOR] 1.95, 95% confidence interval [CI] 1.85-2.04). A diagnosis of VCI was also associated with cesarean delivery (aOR 1.17, 95% CI 1.12-1.23), SGA (aOR 1.93, 95% CI 1.83-2.04), and FDIU (aOR 3.96, 95% CI 3.21-4.89). Conclusion: The presence of VCI was associated with adverse pregnancy outcomes.