Evaluation of Maternal Exposure to PM <sub>2.5</sub> and Its Components on Maternal and Neonatal Thyroid Function and Birth Weight: A Cohort Study
Bibliographic record
Abstract
Background: Particulate matter (PM) air pollution is an environmental risk to public health. The prevalence of thyroid disease during pregnancy has increased rapidly in recent decades, but the available data on the relationships among air pollution, thyroid function, and birth outcomes in pregnant women, particularly in China, are scarce. We aimed to evaluate the association between maternal exposure to PM 2.5 and its components and maternal and neonatal thyroid function and to investigate whether thyroid function acts as a mediator between air pollution and birth weight. Methods: In this prospective birth cohort study, the levels of maternal exposure to PM 2.5 and its components during the first trimester were assessed in 433 pregnant women in Nanjing, China, enrolled during 2014–2015. We evaluated the levels of maternal exposure to PM 2.5 and its six main constituents—organic matter (OM), black carbon (BC), sulfate (SO 4 2− ), nitrate (NO 3 − ), ammonium (NH 4 + ), and soil dust—using the V4.CH.02 product of the Dalhousie University Atmospheric Composition Analysis Group. The maternal serum-free thyroxine (fT4), thyrotropin (TSH), and thyroid peroxidase antibody (TPOAb) levels during the second trimester were measured through electrochemiluminescent microparticle immunoassays. The neonatal TSH levels were detected using an AutoDELFIA Neonatal TSH kit within 72 hours after birth, and the birth weight Z-score of each newborn was estimated. Results: Higher exposure to maternal PM 2.5 and some components (BC and NH 4 + ) decreased the maternal fT4 level ( p < 0.05), and the birth weight Z-score was decreased ( p < 0.05) by higher exposure to maternal PM 2.5 and some components (OM, BC, NO 3 − , and NH 4 + ). A mediation analysis clarified that the maternal fT4 levels explained 15.9%, 18.4%, and 20.9% of the associations of maternal PM 2.5 , BC, and NH 4 + exposure with the birth weight Z-score, respectively ( p < 0.05). After additional sensitivity analyses including only nonpreterm participants ( n = 418) and non-TPOAb-positive participants ( n = 415), the models remained stable. Conclusions: Our results suggest an inverse association between maternal exposure to PM 2.5 and its components and the maternal fT4 levels. Maternal fT4 might act as a mediator between exposure to PM 2.5 and its components and birth weight.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".