Cohort studyindependent cross-checkabstract checked I-ABX-113 standard review
Early antibiotics linked to slightly more childhood obesity
Early-life antibiotic exposure and the risk of overweight and obesity in children.
Overview
Ainonen S et al.. Pediatr Res 2026 · PMID 41792341 · DOI 10.1038/s41390-026-04841-8
Antibiotics in the first 2 years were linked to a 20% higher relative risk of obesity by age 12.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Check timing of antibiotic exposure and child weight
- How was the study done?
Register cohort
- How many people, animals or samples were studied?
33,095 children
- What was actually found?
Exposure in first 2 years linked to more overweight/obesity
- How large was the observed effect?
aHR 1.09 overweight; 1.20 obesity
- What do the results mean in everyday life?
Small relative increase; not proof of cause
- What are the study's limitations?
No family-based control
- What does it say about Elawady's specific claim?
Supports an association
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Whether antibiotics are the cause
Scientific in-depth review
1. Full reference
- Authors
- Ainonen S et al.
- Journal
- Pediatr Res
- Year
- 2026
- Identifier
- PMID 41792341 DOI 10.1038/s41390-026-04841-8
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Authors declare no competing interests (record).
2. Research question
Is the timing of antibiotic exposure associated with childhood overweight and obesity?
3. Study design and population
- Study design
- Cohort study – Population-based cohort linked to registers
- Population
Vaginally delivered children
- Country
Not stated in abstract (national registers)
- Period
Follow-up to 12 years
- Sample size
33,095 children; 595,213 growth measurements
- Inclusion and exclusion criteria
Vaginally delivered children with linked records
4. Methods and endpoints
- Exposure / intervention
Antibiotics before pregnancy, during pregnancy, perinatally, and in the first 24 months
- Comparator
No exposure
- Endpoints
zBMI at 24 months; cumulative incidence of overweight/obesity to 12 years
- Statistical methods
Adjusted hazard ratios
5. Actual results
- Results
Exposure before or at birth: no association. Exposure in first 24 months: higher zBMI at 2 years; aHR 1.09 (95% CI 1.04-1.13) for overweight and 1.20 (1.10-1.31) for obesity.
- Absolute risks
not reported in abstract
- Authors' conclusion
Antibiotic exposure during the first two years of life was associated with childhood overweight and obesity.
6. Strengths
- Many growth measurements
- Timing analysis
7. Weaknesses
- Observational; no sibling control
- Country not explicit in abstract
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Confounding by infections and family factors not addressed in abstract.
9. Assessment of the statistical interpretation
Modest relative associations; CIs log-symmetric.
10. Relevance to the specific claim
Recent large cohort supporting a modest association.
11. Independent contrary findings
No within-family control.
12. Transferability to Germany and Europe
Uncertain: country of the registers not stated in the abstract.
13. Overall methodological judgement
Supports an association of modest size.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | unknown |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality; absolute risk.