Maternal body mass index in early pregnancy and offspring risk of multiple sclerosis: A population-based cohort study
- 1Karolinska Institutet
Abstract
What is already known on this topicO_LIPrenatal and perinatal factors have been linked to offspring MS risk, but evidence has focused mainly on maternal complications or birth outcomes. C_LIO_LIMaternal BMI has been associated with other immune-mediated diseases in offspring, but large-scale evidence linking early-pregnancy BMI to offspring MS risk is lacking. C_LI
What this study addsO_LIIn a nationwide cohort, higher maternal BMI in early pregnancy was associated with increased offspring MS risk. C_LIO_LIThis association persisted after excluding pregnancies with major complications, suggesting it is not fully explained by adverse pregnancy outcomes. C_LIO_LIThese findings provide the first large-scale evidence for the possibility that susceptibility to MS may begin to be shaped in early gestation. C_LI
ObjectiveTo examine whether prospectively recorded maternal BMI in early pregnancy is associated with offspring multiple sclerosis (MS) risk, including childhood-onset and adult-onset MS.
DesignNationwide population-based cohort study.
SettingSwedish national health and demographic registers.
Participants1,524,863 singleton children born in Sweden from 1992 to 2007 and followed through 2025.
ExposuresMaternal BMI recorded at the first antenatal visit, categorised as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), and obesity ([≥]30.0), and also modelled continuously.
Main outcome measuresMS in offspring, identified as at least three ICD-10 G35 codes recorded on separate dates. Cox models estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) adjusting for confounders.
ResultsDuring follow-up, 1539 offspring (0.1%) were diagnosed with MS at a median age of 24 years (interquartile range, 20-27 years). MS incidence rates by maternal BMI category were 0.37 per 10,000 person-years for both underweight, and normal weight, 0.42 for overweight, and 0.45 for obesity. Compared with normal weight women, maternal overweight and obesity were associated with higher hazards of offspring MS, with adjusted HRs of 1.20 (95% CI, 1.05 to 1.37) and 1.35 (95% CI, 1.11 to 1.64), respectively. Onset-specific analyses showed similar findings for adult-onset MS and less precise but directionally consistent estimates for paediatric-onset MS. Each 1-unit increase in maternal BMI was associated with a 3%, 4%, and 3% higher hazard of overall, paediatric-onset, and adult-onset offspring MS, respectively.
ConclusionsIn this population-based cohort study, higher maternal BMI were associated with an increased rate of MS in offspring. The findings provide large-scale prospective evidence that maternal adiposity may be related to offspring MS risk and support further investigation of the prenatal metabolic environment in the early-life origins of MS.
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BibTeX
@misc{xu2026maternal,
title = {{Maternal body mass index in early pregnancy and offspring risk of multiple sclerosis: A population-based cohort study}},
author = {H. Xu and N. Razaz and K. Remaeus and J. Lee and K. Fink and K. A. McKay},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.15.26365617},
url = {https://www.medrxiv.org/content/10.64898/2026.10.15.26365617v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Maternal body mass index in early pregnancy and offspring risk of multiple sclerosis: A population-based cohort study
AU - H. Xu
AU - N. Razaz
AU - K. Remaeus
AU - J. Lee
AU - K. Fink
AU - K. A. McKay
PY - 2026
DA - 2026/10/15
PB - medRxiv
DO - 10.64898/2026.10.15.26365617
UR - https://www.medrxiv.org/content/10.64898/2026.10.15.26365617v1
AB - What is already known on this topicO_LIPrenatal and perinatal factors have been linked to offspring MS risk, but evidence has focused mainly on maternal complications or birth outcomes. C_LIO_LIMaternal BMI has been associated with other immune-mediated diseases in offspring, but large-scale evidence linking early-pregnancy BMI to offspring MS risk is lacking. C_LI What this study addsO_LIIn a nationwide cohort, higher maternal BMI in early pregnancy was associated with increased offspring MS risk. C_LIO_LIThis association persisted after excluding pregnancies with major complications, suggesting it is not fully explained by adverse pregnancy outcomes. C_LIO_LIThese findings provide the first large-scale evidence for the possibility that susceptibility to MS may begin to be shaped in early gestation. C_LI ObjectiveTo examine whether prospectively recorded maternal BMI in early pregnancy is associated with offspring multiple sclerosis (MS) risk, including childhood-onset and adult-onset MS. DesignNationwide population-based cohort study. SettingSwedish national health and demographic registers. Participants1,524,863 singleton children born in Sweden from 1992 to 2007 and followed through 2025. ExposuresMaternal BMI recorded at the first antenatal visit, categorised as underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9), and obesity ([≥]30.0), and also modelled continuously. Main outcome measuresMS in offspring, identified as at least three ICD-10 G35 codes recorded on separate dates. Cox models estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) adjusting for confounders. ResultsDuring follow-up, 1539 offspring (0.1%) were diagnosed with MS at a median age of 24 years (interquartile range, 20-27 years). MS incidence rates by maternal BMI category were 0.37 per 10,000 person-years for both underweight, and normal weight, 0.42 for overweight, and 0.45 for obesity. Compared with normal weight women, maternal overweight and obesity were associated with higher hazards of offspring MS, with adjusted HRs of 1.20 (95% CI, 1.05 to 1.37) and 1.35 (95% CI, 1.11 to 1.64), respectively. Onset-specific analyses showed similar findings for adult-onset MS and less precise but directionally consistent estimates for paediatric-onset MS. Each 1-unit increase in maternal BMI was associated with a 3%, 4%, and 3% higher hazard of overall, paediatric-onset, and adult-onset offspring MS, respectively. ConclusionsIn this population-based cohort study, higher maternal BMI were associated with an increased rate of MS in offspring. The findings provide large-scale prospective evidence that maternal adiposity may be related to offspring MS risk and support further investigation of the prenatal metabolic environment in the early-life origins of MS.
ER -