ObjectiveThe aim of this study was to evaluate the association between prenatally diagnosed isolated single umbilical artery (iSUA) and perinatal outcomes.MethodsWe searched Medline, Embase, the Cochrane Library, and KoreaMed from inception to January 2016, with no language or regional restrictions, for cohort and case-control studies reporting on the relationship of iSUA and perinatal outcomes. We assessed the odds ratios (ORs) and 95% confidence intervals (CIs) for the occurrence of small for gestational age, preterm birth, pregnancy-induced hypertension, neonatal intensive care unit admission, and perinatal mortality in fetuses with iSUA compared with those in fetuses with three vessel cord.ResultsEleven articles totaling 1,731 pregnancies with iSUA met the selection criteria. Studies varied in design, quality, outcome definition, and results. Meta-analysis carried out within predefined groups showed that the presence of an iSUA was associated with small for gestational age (OR, 2.75; 95% CI, 1.97 to 3.83; P<0.00001), preterm birth (OR, 2.10; 95% CI, 1.72 to 2.57; P<0.00001), pregnancy-induced hypertension (OR, 1.62; 95% CI, 1.00 to 2.63; P=0.05), neonatal intensive care unit admission (OR, 2.06; 95% CI, 1.33 to 3.19; P=0.001), and perinatal mortality (OR, 2.29; 95% CI, 1.32 to 3.98; P=0.003).ConclusionPregnancies complicated by iSUA are at increased risk for small for gestational age, preterm birth, pregnancy-induced hypertension, neonatal intensive care unit admission and perinatal mortality. Further, large prospective cohort studies are required to improve the quality of prenatal counseling and the neonatal care for pregnancies with iSUA.
