MATERNAL-FETAL MEDICINE Isolated single umbilical artery is an independent risk factor for perinatal mortality and adverse outcomes in term neonates Gil Gutvirtz 1 • Asnat Walfisch 1 • Ofer Beharier 1 • Eyal Sheiner 1 Received: 24 February 2016 / Accepted: 24 March 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract Objective To determine whether an isolated single umbilical artery (iSUA) is an independent risk factor for perinatal mortality in term neonates with normal estimated fetal weight (EFW) prior to delivery. Method A population-based study was conducted, including all deliveries occurring between 1993 and 2013, in a tertiary medical center. Pregnancies with and without iSUA were compared. Multiple gestations, chromosomal, and structural abnormalities were excluded from the cohort. Only pregnancies delivered at term with normal EFW evaluated prior to delivery were included. Stratified analysis was performed using multiple logistic regression models to evaluate the risk of adverse outcomes and peri- natal mortality for iSUA fetuses. Results During the study period, 233,123 deliveries occurred at ‘‘Soroka’’ University Medical Center, out of which 786 (0.3 %) were diagnosed with iSUA. Different pregnancy complications were more common with iSUA fetuses including: placental abruption (OR = 3.4), true knot of cord (OR = 3.5) and cord prolapse (OR = 2.8). Induction of labor and cesarean delivery were also more common in these pregnancies (OR = 1.5 and OR = 1.9, respectively). iSUA neonates had lower Apgar scores at 1 and 5 min (OR = 1.8, OR = 1.9, respectively) compared to the control group and perinatal mortality rates were higher both antenatally (IUFD, OR = 8.1) and postnatally (PPD, OR = 6.1). Conclusion iSUA appears to be an independent predictor of adverse perinatal outcomes in term neonates. Keywords SUA Á Term pregnancy Á Pregnancy complications Á Intra-uterine fetal death Á Post-partum death Introduction The umbilical cord typically contains three vessels: one vein that carries oxygenated blood from the placenta to the fetus, and two arteries that carry the blood from the fetus back to the placenta. Single Umbilical Artery (SUA) refers to a variation of the umbilical cord in which there is only one artery instead of the normal two. It is a common variation of the umbilical cord with a reported incidence of 0.2–2 % of pregnancies [1]. SUA was shown to be asso- ciated with several fetal structural and chromosomal abnormalities (including cardiac, gastrointestinal and renal anomalies) leading to fetal and neonatal complications [2]. Thus, the American Institute of Ultrasound in Medicine (AIUM) recommends imaging of the umbilical cord including the number of vessels in the cord during the routine prenatal ultrasound examinations [3]. If SUA is identified, a targeted ultrasound is warranted to rule out known associated anomalies. The term isolated SUA (iSUA) refers to fetuses identi- fied with SUA and no other apparent abnormality on ultrasound. iSUA is more common than non-isolated SUA [4–7], and the significance of this finding is controversial. Several studies evaluating the significance of iSUA revealed associations with fetal growth restriction, preterm delivery and low birth weight [1, 2, 8, 9], although others failed to establish such associations [10–13]. Recent & Eyal Sheiner Sheiner@bgu.ac.il 1 Department of Obstetrics and Gynecology, Soroka University Medical Center, Ben-Gurion University of the Negev, 151 Izak Rager Ave, 84101 Beer-Sheva, Israel 123 Arch Gynecol Obstet DOI 10.1007/s00404-016-4088-8