Christine Dahl

• Barak, Eden Nordvold; Kolskår, Knut-Kristian; Dahl, Christine; Alnæs, Dag; Andreassen, Ole & Nærland, Terje [Show all 9 contributors for this article] (2026). Birth Weight and Neurodevelopmental Disorders Across Diagnostic Categories: A Registry-Based Case–Control Study in Clinically Ascertained Samples | Child Psychiatry & Human Development | Springer Nature Link. Child Psychiatry and Human Development. ISSN 0009-398X. doi: 10.1007/s10578-026-02090-8. Full text in Research Archive Show summary

  Increasing prevalence of neurodevelopmental disorders (NDDs) is a growing public health concern. Identifying early risk markers may facilitate earlier intervention and reduce long-term burden. Although birth weight has been widely studied in relation to NDDs, evidence from clinically ascertained samples with single and overlapping diagnoses remains limited. In this case-control study, we compared birth weight between clinically referred individuals with intellectual disability (ID), autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD) from the Norwegian BUPgen registry (n = 720) and a population-based sample from the Norwegian Mother, Father and Child Cohort Study (MoBa) (n = 98,716). Perinatal data were obtained through linkage to the Medical Birth Registry of Norway. Associations were examined using logistic regression adjusted for gestational age, sex, and parental age. Additional analyses assessed interactions by sex and parental age, and birth weight categories. For each 100 g decrease in birth weight, odds significantly increased for the groups any NDD (one or more NDD diagnoses; OR = 1.04) and multiple diagnoses (two or more co-occurring NDDs; OR = 1.07). In diagnosis specific analyses, odds significantly increased for ID (OR = 1.15) and ASD (OR = 1.03). No interactions were observed. In categorical analyses, low birth weight was associated with higher odds of ID (OR = 8.27, p < 0.001), multiple diagnoses (OR = 4.96, p < 0.001), and any NDD (OR = 2.11, p = 0.002). No associations were observed for high birth weight. These findings support low birth weight as an early marker of neurodevelopmental vulnerability across NDD outcomes. Lower birth weight was associated with higher odds of ID, ASD, multiple diagnoses and any NDD, but not ADHD. Associations were strongest and most consistent for ID and comorbid presentations, indicating heterogeneity across diagnostic categories. Increased risk was primarily observed at low birth weight, with no associations for high birth weight. Findings support birth weight as an early marker of neurodevelopmental vulnerability in a clinically ascertained sample.

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