Standardization of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) to gestational age in early pregnancy and associations with clinical outcomes
Authors' conclusion
Full standardization of TSH and FT4 to gestational age either does not affect or weakens their associations with clinical outcomes, suggesting that accounting for gestational age offers no benefit with regard to identifying high-risk thyroid dysfunction during early pregnancy.
Study context
- Population
- Pregnant women with TSH, FT4 and TPOAb data in early pregnancy (median 13.2 weeks, 95% range 9.8–17.6)
- Participants
- 5,675 women
- Exposure
- Gestational age-standardized vs non-standardized TSH and FT4
- Outcome
- Associations of TSH and FT4 with gestational age and effect of standardization
- Follow-up
- Early pregnancy
Methodological detailspopulation-based
- Population-based
Main finding
As reported in the abstract
- Difference in mean TSH with gestational age at blood sampling (positive association); P < 0.001
- +9.6%
- Difference in mean FT4 with gestational age at blood sampling (negative association); P < 0.001
- −20.2%
- TSH standardization: reclassified as normal TSH
- 36 (9.9%)
- TSH standardization: reclassified as abnormal TSH
- 27 (0.5%)
- FT4 standardization: reclassified as normal FT4
- 62 (20.3%)
- FT4 standardization: reclassified as abnormal FT4
- 57 (1.1%)
- Attenuation of associations with any outcome (pre-eclampsia, premature delivery, birth weight, offspring IQ) after standardization vs non-standardized TSH or FT4
- up to 71%
Observational data: associations, not effects.
Original publication
Standardization of TSH and FT4 to gestational age in early pregnancy and associations with clinical outcomes. Eur Thyroid J. Published 15 July 2025. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →