Breastfeeding and Risk of Multiple Sclerosis: A Systematic Review and Meta-Analysis of Observational Studies
Bibliographic record
Abstract
INTRODUCTION: The causes of multiple sclerosis (MS) are not fully understood, yet. Genetic predisposition, environmental and lifestyle factors as well as an interplay thereof constitute relevant factors in the development of MS. Especially early-life risk factors such as having been breastfed may also be of relevance. Breast milk provides the newborn not only with essential nutrients and vitamins but also with numerous immune-active molecules, metabolites, oligosaccharides, and microbial components that are important for the development of the immune system. We present a systematic review and meta-analysis on the influence of having been breastfed during infancy on the risk of developing MS. METHODS: The databases MEDLINE, Cochrane Library, and Web of Science were systematically searched for studies on breastfeeding and MS published between database inception and May 18, 2022. Observational studies comparing persons with MS to healthy controls with regard to having been breastfed during the first 2 years of life were eligible for inclusion. A random effects meta-analysis was calculated to estimate pooled effect sizes using the Mantel-Haenszel method for dichotomous outcomes. The Newcastle-Ottawa Scale was used for quality analysis. RESULTS: 15 studies (13 case-control, 2 cohort) were included of which 12 were rated as high quality. The meta-analysis of crude odds ratios (ORs) yielded a risk estimate of ORcrude = 0.82 (95% confidence interval [CI]: 0.70-0.96) for MS in breastfed versus non-breastfed individuals with substantial heterogeneity (I2 = 68.2%). Using adjusted OR, when available, reduced heterogeneity (I2 = 48.9%) and resulted in an ORadjusted = 0.86 (95% CI: 0.75-0.99). Restricting the analysis to studies with high-quality scores (i.e., ≥6/9 points) resulted in a combined ORcrude of 0.79 (95% CI: 0.66-0.94) and an ORadjusted = 0.83 (95% CI: 0.71-0.98), respectively. DISCUSSION/CONCLUSION: The meta-analysis showed a small protective effect of having been breastfed on MS risk. This adds to the knowledge that breastfeeding is beneficial for the immunological health of a child. Future studies on the influence of having been breastfed on MS risk should apply a uniform definition of breastfeeding and investigate possible sex-specific aspects.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.072 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.026 | 0.003 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".