Cohort studyindependent cross-checkabstract checked★ key study I-LEG-130 standard review
Soy formula in infancy and menstrual pain
Soy-based infant formula feeding and menstrual pain in a cohort of women aged 23-35 years.
Overview
Upson K et al.. Hum Reprod 2019 · PMID 30412246 · DOI 10.1093/humrep/dey303
Women fed soy formula as babies more often reported severe period pain.
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?
Test soy formula and menstrual pain.
- How was the study done?
Cohort, recalled exposure.
- How many people, animals or samples were studied?
1,553 women.
- What was actually found?
Higher pain indicators.
- How large was the observed effect?
RR 1.4-1.5.
- What do the results mean in everyday life?
A possible long-term hormonal effect of soy formula.
- What are the study's limitations?
Recall bias.
- What does it say about Elawady's specific claim?
Supports concern in C-LEG-10.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
It does not concern legumes eaten by children or adults.
Scientific in-depth review
1. Full reference
- Authors
- Upson K et al.
- Journal
- Hum Reprod
- Year
- 2019
- Identifier
- PMID 30412246 DOI 10.1093/humrep/dey303 · PMC6296212
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref works API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH intramural and ARRA funding; no conflicts declared.
2. Research question
Is infant soy formula feeding associated with menstrual pain in adulthood?
3. Study design and population
- Study design
- Cohort study – Cross-sectional analysis within a cohort (SELF) with retrospective exposure recall
- Population
African-American women aged 23-35 y
- Country
USA (not further specified in abstract)
- Period
SELF enrolment
- Sample size
1,553 with exposure data
- Inclusion and exclusion criteria
SELF participants.
4. Methods and endpoints
- Exposure / intervention
Ever soy formula in infancy (maternal-assisted recall)
- Comparator
Not fed soy formula
- Endpoints
Indicators of menstrual pain
- Statistical methods
Log-binomial regression adjusted for age and maternal education
5. Actual results
- Results
Ever use of hormonal contraception for menstrual pain RR 1.4 (1.1-1.9); moderate/severe pain with 'most periods' in early adulthood RR 1.5 (1.1-2.0), not with 'every period'.
- Absolute risks
Not reported
- Authors' conclusion
Soy formula feeding is associated with several indicators of severe menstrual pain.
6. Strengths
- Large cohort
7. Weaknesses
- Retrospective recall of infant feeding and pain
- Multiple pain indicators
- Abstract only
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
Recall bias; limited adjustment.
9. Assessment of the statistical interpretation
Modest RRs; multiplicity across indicators.
10. Relevance to the specific claim
Supports the concern that infant soy formula may have hormone-related consequences (C-LEG-10), consistent with Strom 2001's menstrual findings.
11. Independent contrary findings
12. Transferability to Germany and Europe
Plausibly applicable.
13. Overall methodological judgement
Modest, replicated signal for menstrual outcomes; clinical harm still uncertain.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality.