Preconception body mass index and maternal thyroid function: a longitudinal observational study
Authors' conclusion
Higher p-BMI is associated with a persistently less favorable maternal thyroid hormone profile throughout pregnancy. Low FT4 concentrations during early pregnancy showed the strongest association with obstetric risk, supporting further investigation into early thyroid assessment in higher-risk populations.
Study context
- Population
- Pregnant women stratified by preconception BMI; thyroid function at ≤13 gestational weeks and two later time points
- Participants
- 1,107 women
- Exposure
- Overweight and obese vs normal-weight preconception BMI
- Outcome
- Maternal thyroid function (TSH and FT4) longitudinally over pregnancy
Methodological detailslongitudinal, observational
- Longitudinal
- Observational
Main finding
As reported in the abstract
early pregnancy and across gestation
- At early pregnancy, overweight (OW) and obese (OB) had lower free thyroxine (FT4) and higher TSH than normal weight (NW)
- Across gestation, FT4 declined and TSH increased in all BMI categories, with persistently lower FT4 and higher TSH with higher BMI
- No significant preconception body mass index (p-BMI) × gestational period interaction
Observational data: associations, not effects.
Further findings
Composite adverse obstetric outcome by first-trimester low FT4 (exploratory)
| OR (95% CI) | P value | ||
|---|---|---|---|
| Low FT4Independently associated · exploratory analysis | 2.04 (1.32–3.11) | P = 0.001 | |
| 0.20.5125Odds ratio (log scale) |
Composite adverse obstetric outcome by first-trimester elevated TSH (exploratory)
| OR (95% CI) | P value | ||
|---|---|---|---|
| Elevated TSHExploratory analysis | 1.71 (1.04–2.77) | P = 0.03 | |
| 0.20.5125Odds ratio (log scale) |
Original publication
Preconception body mass index and maternal thyroid function: a longitudinal observational study. Eur Thyroid J. Published 20 May 2026. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →