Velamentous or marginal cord insertion and the risk of spontaneous preterm birth, prelabor rupture of the membranes, and anomalous cord length, a population-based study.

Velamentous and, to a lesser extent, marginal cord insertions were associated with increased risk of PROM, pPROM, SPTB, and short cord. This suggests a common pathogenesis behind altered function of the membranes, cord, and placenta. The decline in SPTB could not be explained by the reduction in the occurrence of anomalous cord insertion.