Detection of enlarged yolk sac on early ultrasound is associated with adverse pregnancy outcomes.

Pregnancies with mean yolk sac diameter>or=5 mm on early ultrasound require monitoring and counseling about a threefold increased risk for first-trimester loss independent of maternal risk factors such as age, body mass index, polycystic ovary syndrome, smoking, and diabetes. In addition, our study shows for the first time that enlarged yolk sac diameter may be associated with an increased risk of preterm delivery. Copyright (c) 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.