Objective: A single umbilical artery (SUA) is associated with a risk of adverse perinatal outcome. Around 11% of fetuses with SUA present with an associated major anomaly, including those of the central nervous system. However, studies on the associations between SUA and childhood neurodevelopmental disorders (NDD), such as intellectual disability (ID), attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, epilepsy, impaired hearing and impaired vision, are limited. We aimed to evaluate the risk of NDD in children presenting with an isolated SUA (iSUA) at birth and the possible impact of sex, and to examine the extent to which gestational age at birth and birth weight mediate the effect of iSUA on NDD.
Methods: This was a historical national cohort study linking data from the Medical Birth Registry of Norway with other mandatory national registries. We included all singleton live births in Norway between 1 January 1999 and 31 December 2013, and follow-up of the study cohort was concluded on 31 December 2019. We included all newborns diagnosed with iSUA. Data regarding NDD diagnosis were obtained from the Norwegian National Insurance Scheme and the Norwegian Patient Registry. We used multilevel logistic regression to calculate odds ratios (ORs) with 95% CIs, and performed sex-stratified analyses. A causal mediation analysis of the relationship between iSUA and NDD with preterm birth (live birth < 37 weeks' gestation) and small-for-gestational age (SGA) (birth weight < 5th percentile) was performed.
Results: The cohort of 858 397 singleton live births included 3532 cases diagnosed with iSUA (0.41%), of which 1802 (51.3%) were male, 253 (7.2%) were born preterm and 249 (7.0%) were SGA. iSUA was associated with increased odds of subsequent ID (OR, 1.56 (95% CI, 1.09-2.23)) and ADHD (OR, 1.22 (95% CI, 1.02-1.47)), but there was no observed association with other NDD. In sex-stratified analyses, the associations with iSUA were observed in females but not in males. Preterm birth and SGA were each found to mediate < 10% of the total effect of iSUA on ID.
Conclusion: iSUA was weakly associated with ID and ADHD, but not with other NDD. These associations were influenced by sex and were mediated by < 10% by preterm birth or SGA. The absence of associations of iSUA with other NDD is reassuring, and this finding is useful in the counseling of expectant parents of fetuses with iSUA. © 2026 International Society of Ultrasound in Obstetrics and Gynecology.
Keywords: ADHD; NDD; attention deficit hyperactivity disorder; causal mediation analysis; children; intellectual disability; neurodevelopmental disorders; newborn; population study; pregnancy; umbilical arteries.
© 2026 International Society of Ultrasound in Obstetrics and Gynecology.