Urinary Iodine Concentration and Thyroid Hormone Metabolism in Pregnant Women and Neurodevelopment in Their Children: A Longitudinal Canadian Birth Cohort
Bibliographic record
Abstract
Background/Objectives: Iodine is essential for thyroid hormone (TH) synthesis, and THs in pregnant women are critical for fetal brain development. It is unclear whether urinary iodine concentrations (UICs) are associated with thyroid parameters in pregnant women and neurodevelopment in their 3–4-year-old children. Methods: In the Canadian Maternal–Infant Research on Environmental Chemicals (MIREC) cohort, we categorized UIC adjusted for urinary creatinine (UIC/Cr) in the first two trimesters as <150, 150–500, or ≥500 µg/g. We used multivariable regression to quantify associations between UIC/Cr and thyroid parameters in maternal plasma (n = 1501), including thyroid stimulating hormone (TSH), total T4 (tT4), free T4 (fT4), thyroglobulin (Tg) and Tg antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb). We defined positive thyroid autoantibodies as TgAb ≥ 4.11 or TPOAb ≥ 5.61 IU/mL. We also examined the associations between UIC/Cr with the Wechsler Preschool and Primary Scale of Intelligence (n = 503), Behavior Assessment System for Children (n = 751), and the Social Responsiveness Scale (n = 498). Results: Twenty-two percent of women had UIC/Cr < 150 and 17% ≥ 500 µg/g. UIC/Cr was not associated with TSH, tT4, or fT4. After excluding women with positive thyroid autoantibodies, those with UIC/Cr < 150 µg/g had higher tT4 compared to those with 150–500 µg/g. Compared to women with UIC/Cr 150–500 µg/g, those with UIC/Cr < 150 had higher Tg and, those with UIC/Cr ≥ 500 had less frequent positive thyroid autoantibodies. Neurodevelopmental outcomes were not associated with maternal Tg, nor did they differ for maternal UIC/Cr < 150 and ≥500 compared to 150–500 µg/g. Conclusions: In this cohort, Tg and tT4 were higher in women with UIC/Cr < 150 µg/g compared to those with UIC/Cr 150–500 µg/g. Urinary iodine in pregnant women was not associated with neurodevelopment in their 3–4-year-old children.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".