The Effect of Tobacco Exposure on Maternal and Fetal Thyroid Function
Bibliographic record
Abstract
Smoking has adverse effects on thyroid function in nonpregnant women. For example, a previous study found a small but statistically significant decrease in the concentrations of thyrotropin (TSH) in smokers compared to nonsmokers, and a recent meta-analysis found that the risk of Graves’ disease was three-fold greater among smokers than in those who had never smoked; cessation of smoking decreased the risk. However, data on the effects of smoking during pregnancy on maternal and neonatal thyroid function have been conflicting. This prospective cohort study evaluated the effect of smoking on maternal and neonatal thyroid function in 104 healthy women (83 nonsmokers and 21 smokers) undergoing elective cesarean section for term singleton infants during the years 2002–2004. The smoker to nonsmoker ratio (4:1) reflected the general rates of smoking during pregnancy. Mothers who smoked were significantly younger than nonsmokers (median age 29.5 versus 33.0 years, respectively, P ≤ .023), and had significantly lighter infants (3250 gm versus 3456 gm, respectively, P ≤ .011). Smokers had significantly lower maternal TSH concentrations than nonsmokers (median 1.75 mIU/liter versus 2.15 mIU/liter, respectively, P ≤ .007), but there was no difference in free thyroxine (FT4) concentrations (median 9.59 pmol/liter versus 9.56 pmol/liter (P = .755). There was a correlation between the number of cigarettes smoked per day and the maternal TSH concentrations (R = –.427; P ≤ .05). Umbilical venous TSH and FT4 concentrations were similar in infants of nonsmokers and smokers (P = .049). This is the first study to show that women who smoke during pregnancy have significantly lower TSH concentrations than nonsmokers.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".