A GROWING body of evidence suggests that multiple sclerosis risk may be influenced long before symptoms appear, with new national data indicating that birth size and maternal diabetes during pregnancy are linked to adult-onset disease development.
Prenatal Exposures in a National Norwegian Cohort
Researchers analysed national registry data from Norway to investigate whether adverse pregnancy outcomes are associated with multiple sclerosis risk later in life. The closed cohort included all live births recorded between 1967 and 1989 and linked maternal and offspring health records across more than five decades. The analysis focused on several prenatal exposures, including preterm birth, being born small or large for gestational age, hypertensive disorders of pregnancy, placental abruption, and maternal diabetes.
Participants were followed from January 2009 until December 2019, capturing adult-onset diagnoses of multiple sclerosis and allowing assessment of long-term neurological outcomes in a population-based setting.
Birth Size and Diabetes as Predictors of Adult Disease
Among 1,166,731 individuals included in the analysis, 4295 cases of multiple sclerosis were identified. Being born large for gestational age was associated with increased multiple sclerosis risk, with a hazard ratio of 1.13 (95% CI, 1.03-1.25). In contrast, being born small for gestational age was associated with reduced multiple sclerosis risk, with a hazard ratio of 0.88 (95% CI, 0.78-0.98). Offspring exposed to maternal diabetes experienced more than double the multiple sclerosis risk, with a hazard ratio of 2.15 (95% CI, 1.37-3.37).
Preterm birth, placental abruption, and hypertensive disorders of pregnancy were not associated with altered risk, suggesting that metabolic and growth-related exposures may play a more substantial role than obstetric complications.
Implications For Early Risk Identification
These findings indicate that susceptibility to multiple sclerosis risk may originate in the prenatal period. For clinicians, the results reinforce the importance of maternal metabolic health and monitoring fetal growth trajectories. Enhanced screening and management of gestational diabetes may represent an opportunity to mitigate long-term neurological risk in offspring.
Reference
Wolfova K et al. Maternal pregnancy outcomes and offspring risk of adult-onset multiple sclerosis. JAMA Neurol. 2026;DOI:10.1001/jamaneurol.2025.5255.
