SynthesisThe Journal of clinical endocrinology and metabolism2022
TSH and FT4 Reference Intervals in Pregnancy: A Systematic Review and Individual Participant Data Meta-Analysis.
Synthesis in The Journal of clinical endocrinology and metabolism, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 27 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
27 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Defining Gestational Thyroid Dysfunction Through Modified Nonpregnancy Reference Intervals: An Individual Participant Meta-analysis.The Journal of clinical endocrinology and metabolism · 2024Pooled it
- The impact of thyroid autoimmunity on pregnancy outcomes in women with unexplained infertility undergoing intrauterine insemination: a retrospective single-center cohort study and meta-analysis.Frontiers in endocrinology · 2024Pooled it
- Reference Ranges and Determinants of Thyroid Function and TSH Receptor Antibodies During Early Pregnancy in Nepal.Clinical endocrinology · 2025Trial
- Association of Maternal Thyroid-stimulating Hormone Levels with Psychological Well-being, Sexual Function, and Quality of Life During Pregnancy.Reproductive sciences (Thousand Oaks, Calif.) · 2026Article
- Emotion-Regulation Difficulties and Skills in the Cross-Sectional Association Between Thyroid Function and Antenatal Distress in Hypothyroid Pregnancy.Healthcare (Basel, Switzerland) · 2026Article
- Pregnancy-specific Reference Intervals for TSH and FT4: Novel Insights From Preconception-gestation Longitudinal Data.The Journal of clinical endocrinology and metabolism · 2026Article
- Association of hypothyroidism with adverse pregnancy outcomes: a single-center cohort study in an iodine-sufficient country.Endocrine journal · 2026Article
- Global and Indian perspectives on trimester-specific reference intervals for thyroid hormones in pregnant women: a systematic review.Thyroid research · 2026Review
- Iodine deficiency in the first pregnancy trimester and intelligence in adolescence.European journal of nutrition · 2026Article
- First trimester of pregnancy TSH laboratory specific reference intervals established by an indirect method.Biochemia medica · 2026Observational
- Maternal thyroid function in the first half of pregnancy and neurodevelopmental outcomes in early adolescence in the Amsterdam Born Children and their Development (ABCD) cohort.Comprehensive psychoneuroendocrinology · 2026Article
- Canadian Endocrinologists' Perspectives on Treatment With Thyroid Hormone Substitutions in Euthyroid and Hypothyroid Patients: A 2023 THESIS Questionnaire Survey.Clinical endocrinology · 2025Article
- Investigating factors associated with thyroid hormone measurements during pregnancy.European thyroid journal · 2025Article
- Standardization of TSH and FT4 to gestational age in early pregnancy and associations with clinical outcomes.European thyroid journal · 2025Article
- EndoCompass Project: Research Roadmap for Thyroid Endocrinology.Hormone research in paediatrics · 2025Review
- Thyroid function monitoring during pregnancy in euthyroid women with thyroid autoimmunity.Endocrine connections · 2024Article
- Consequences of undertreatment of hypothyroidism.Endocrine · 2024Review
- TSH and FT4 Reference Interval Recommendations and Prevalence of Gestational Thyroid Dysfunction: Quantification of Current Diagnostic Approaches.The Journal of clinical endocrinology and metabolism · 2024Article
- Influence of thyroid autoimmunity at various clinical stages of hypothyroidism on the risk of miscarriage before 20 weeks of gestation.Hormones (Athens, Greece) · 2023Article
- Trimester-specific reference intervals for thyroid function parameters in pregnant Caucasian women using Roche platforms: a prospective study.Journal of endocrinological investigation · 2023Article
Corrections and comments
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Authors and funding
49 authors.
Funding
Abstract
contextInterpretation of thyroid function tests during pregnancy is limited by the generalizability of reference intervals between cohorts due to inconsistent methodology.
objective(1) To provide an overview of published reference intervals for thyrotropin (TSH) and free thyroxine (FT4) in pregnancy, (2) to assess the consequences of common methodological between-study differences by combining raw data from different cohorts.
methods(1) Ovid MEDLINE, EMBASE, and Web of Science were searched until December 12, 2021. Studies were assessed in duplicate. (2) The individual participant data (IPD) meta-analysis was performed in participating cohorts in the Consortium on Thyroid and Pregnancy.
results(1) Large between-study methodological differences were identified, 11 of 102 included studies were in accordance with current guidelines; (2) 22 cohorts involving 63 198 participants were included in the meta-analysis. Not excluding thyroid peroxidase antibody-positive participants led to a rise in the upper limits of TSH in all cohorts, especially in the first (mean +17.4%; range +1.6 to +30.3%) and second trimester (mean +9.8%; range +0.6 to +32.3%). The use of the 95th percentile led to considerable changes in upper limits, varying from -10.8% to -21.8% for TSH and -1.2% to -13.2% for FT4. All other additional exclusion criteria changed reference interval cut-offs by a maximum of 3.5%. Applying these findings to the 102 studies included in the systematic review, 48 studies could be used in a clinical setting.
conclusionWe provide an overview of clinically relevant reference intervals for TSH and FT4 in pregnancy. The results of the meta-analysis indicate that future studies can adopt a simplified study setup without additional exclusion criteria.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.