Thyroid Laboratory Testing and Management in Women on Thyroid Replacement Before Pregnancy and Associated Pregnancy Outcomes
Bibliographic record
Abstract
Background: Women with hypothyroidism before pregnancy often require an increase in their levothyroxine dosage to maintain a euthyroid state during pregnancy. The objectives of this study were to investigate: (i) the frequency and distribution of thyrotropin (TSH) testing and levothyroxine dosage adjustment by gestational age, (ii) the magnitude of levothyroxine increase by the underlying etiology of hypothyroidism, and (iii) the relationship of overtreatment or undertreatment during pregnancy with adverse pregnancy outcomes among women using thyroid replacement before pregnancy. Methods: A retrospective cohort study of pregnancies in women on thyroid replacement before pregnancy in Alberta, Canada, was performed. Women using thyroid replacement anytime during the two years before pregnancy who delivered between October 2014 and September 2017 were included. Delivery records, physician billing, and laboratory and pharmacy administrative data were linked. Outcomes included characteristics of TSH testing, levothyroxine dosing, and pregnancy outcomes. The frequency and gestational timing of TSH testing and levothyroxine adjustments were calculated. Multiple logistic regression was used to test whether pregnancies with TSH <0.10 mIU/L (overtreatment) or TSH ≥10.00 mIU/L (undertreatment) compared with control pregnancies (TSH 0.10–4.00 mIU/L) were associated with adverse pregnancy and neonatal outcomes. Results: Of the 10,680 deliveries, 8774 (82.2%) underwent TSH testing at least once during pregnancy, at a median gestational age of six weeks. An adjustment of levothyroxine dosage was made for 4321 (43.7%) during pregnancy. TSH in pregnancy below 0.10 mIU/L increased the odds of preterm delivery when compared with control pregnancies (adjusted odds ratio, 2.14 [95% confidence interval 1.51–2.78]). TSH ≥10.00 mIU/L during pregnancy was not associated with any adverse pregnancy or neonatal outcomes in the multivariable analysis. Conclusions: Although most women on thyroid replacement before conception had TSH measured at some point during pregnancy, it is concerning that 17.8% did not. Levothyroxine overtreatment in pregnancy was associated with preterm delivery. These findings suggest that clinicians should be careful to avoid overtreatment with levothyroxine in pregnancy.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".