Supplementary Material for: Neurobehavioral Outcomes at 10 Years of Age Following Delayed Umbilical Cord Clamping – a follow-up study after a randomized trial

Introduction: To explore long-term behavioral consequences of early versus delayed cord clamping (CC) in school-aged children. The hypothesis was that early CC would be associated with an increased risk of symptoms associated with attention deficit hyperactivity disorder (ADHD) due to the lower iron stores following early CC compared with delayed CC.
Methods: Exploratory, long-term follow-up study of a randomized controlled trial in Sweden. Full-term, vaginally born, neonates to healthy mothers were originally included and randomized to either early (≤10 sec) or delayed (≥180 sec) CC. At 10 years of age, scores from the screening questionnaire Swanson Nolan and Pelham Scale IV (SNAP-IV), that identifies symptoms suggestive of ADHD (but do not diagnose ADHD), were compared between groups of early and delayed CC.
Results: We assessed 139/382 (36.4%) children, 64 early CC and 75 delayed CC. No significance in total score and subgroup scores of SNAP-IV was seen when comparing early and delayed CC. In the primary outcome, total scores, mean (standard deviation), of early CC was 14.64 (13.94) and for delayed CC 13.59 (13.41), P = .65.
Conclusion: Timing of umbilical CC and iron status were not associated with symptoms associated with ADHD in 10-year-old children. Studies with higher follow-up rates and in populations with high prevalence of iron deficiency are needed to verify or discard the findings. Understanding if delayed CC have long-lasting neurobehavioral or neurodevelopmental effects can help develop guidelines and programmes about neonatal care.