Cohort studyindependent cross-checkabstract checked★ key study I-ABX-110 standard review
Antibiotics in babies linked to very slightly higher weight at age 5
Early Antibiotic Exposure and Weight Outcomes in Young Children.
Overview
Block JP et al.. Pediatrics 2018 · PMID 30381474 · DOI 10.1542/peds.2018-0290
Children given antibiotics before age 2 were very slightly heavier at age 5.
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 whether early antibiotics relate to weight at 5
- How was the study done?
Health-record cohort
- How many people, animals or samples were studied?
362,550 children
- What was actually found?
Very slightly higher weight
- How large was the observed effect?
BMI z +0.04; OR 1.05
- What do the results mean in everyday life?
The difference is tiny for an individual child
- What are the study's limitations?
Cannot separate effect of infections
- What does it say about Elawady's specific claim?
Supports a small association, not a large causal effect
- Do the results apply to Germany and Europe?
Moderate
- What can explicitly not be concluded from this study?
Whether antibiotics cause the difference
Scientific in-depth review
1. Full reference
- Authors
- Block JP et al.
- Journal
- Pediatrics
- Year
- 2018
- Identifier
- PMID 30381474 DOI 10.1542/peds.2018-0290
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref
- Retracted
- no
- Corrections
ErratumIn Pediatrics 2019;143(2):e20183555 (PubMed); erratum content not reviewed; no retraction
- Extent checked
- abstract only
- Conflicts of interest and funding
One collaborator advisory/consultant relationships with Merck and Pfizer; funded by PCORI and NIH (PubMed record).
2. Research question
Is antibiotic use before 24 months associated with weight outcomes at 5 years?
3. Study design and population
- Study design
- Cohort study – Multicentre retrospective cohort (PCORnet electronic health records)
- Population
Children with same-day height and weight measurements, 35 US institutions
- Country
USA
- Period
2009-2016
- Sample size
362,550
- Inclusion and exclusion criteria
Measurements at 0-<12, 12-<30 and 48-<72 months
4. Methods and endpoints
- Exposure / intervention
Any antibiotic use <24 months
- Comparator
No antibiotics
- Endpoints
BMI z-score and overweight/obesity at about 5 years
- Statistical methods
Adjusted regression
5. Actual results
- Results
58% received >=1 antibiotic <24 months; 28% overweight/obese at 5 years. Children without complex chronic conditions: BMI z-score +0.04 (95% CI 0.03-0.05); OR overweight/obesity 1.05 (1.03-1.07) for any vs no antibiotics.
- Absolute risks
OR 1.05 at 28% prevalence = about 1 percentage point (recalculated, approximate)
- Authors' conclusion
Antibiotic use at <24 months was associated with a slightly higher body weight at 5 years.
6. Strengths
- Very large
- Measured height and weight
7. Weaknesses
- Observational; confounding by indication (infections) not removed
- Small effect
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
Residual confounding by infections and family factors possible.
9. Assessment of the statistical interpretation
Statistically precise but clinically very small effect (BMI z +0.04).
10. Relevance to the specific claim
Largest single cohort: a real but very small association.
11. Independent contrary findings
Effect size argues against 'the boy gets fat'.
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Supports only a tiny association, not a clinically important causal effect.
| 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 | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality.