Third stage of labor risks in velamentous and marginal cord insertion: A population-based study

Abstract

Objective To assess whether anomalous cord insertion is associated with risk of complications in the third stage of labor. Design A population-based study. Setting Norwegian Medical Birth Register. Population All singleton births (gestational age >16 weeks and <45 weeks) during the period 1999-2011 (n = 738 443 singletons). Deliveries by cesarean were excluded, leaving 628 680 vaginal singleton deliveries for the analyses. Methods Calculation of odds ratios for complications in the third stage of labor (postpartum hemorrhage, manual delivery of the placenta, curettage) in velamentous and marginal cord insertion by logistic regression with adjustment for confounders. Main outcome measures Complications in the third stage of labor, postpartum hemorrhage, manual placental removal and curettage. Results Anomalous cord insertion was associated with an increased risk of complications in the third stage of labor, the risk being higher for velamentous than for marginal insertion. The risks persisted after adjusting for possible confounding factors. Velamentous cord insertion carried a 5.6% risk of a need for manual removal of the placenta, compared with the risk of 1.1% for nonvelamentous insertion (odds ratio = 5.21, 95% confidence interval 4.71-5.76) in vaginal delivery, and we found increased risks of curettage (odds ratio = 3.29, 95% confidence interval 2.87-3.77) and postpartum hemorrhage (odds ratio = 2.06, 95% confidence interval 1.77-2.39). Conclusions Marginal and especially velamentous cord insertion is associated with an increased risk of hemorrhage in the third stage of labor, need for manual removal of the placenta and curettage. Anomalous cord insertion can be identified prenatally and so possibly influence obstetric management.