Air Pollution Mixture and Folate Status Indicators among Pregnant Women in Canada: Maternal-Infant Research on Environmental Chemicals (MIREC) Study, 2008 to 2011
Bibliographic record
Abstract
BackgroundFolic acid (FA) has been reported to modify associations between air pollutants and autism, but no study has investigated whether air pollutants are associated with maternal folate status. ObjectiveWe estimated associations between an air pollution mixture and maternal folate status among pregnant women in Canada. MethodsWe enrolled pregnant women (n=1,983) in 10 cities in Canada from 2008 to 2011 in a prospective cohort.We estimated mean daily concentrations of nitrogen dioxide (NO2), ozone (O3), fine particulate matter (PM2.5), and sulfur dioxide (SO2) at maternal residences for 180 days preceding first and third trimester visits (ranges: 6-14 and 32-34 gestational weeks, respectively).At both visits, we measured plasma 5-methyltetrahydrofolate, unmetabolized folic acid, and nonmethylated folate concentrations (5MTHF, UMFA, NMF) and proportions (%5MTHF, %UMFA, %NMF).We used Bayesian weighted quantile sum regression to estimate expected differences in folate measures per one-quartile difference in the air pollution mixture and weights for the mixture components.We stratified by fetal sex and FA supplementation. ResultsAmong complete cases in the first and third trimesters (n=927 and 838, respectively), median (IQR) plasma total folate was similar between the first trimester (96.9 [78.6, 119.0] nmol/L) and J o u r n a l P r e -p r o o f the third trimester (99.6 [76.0, 135.0] nmol/L).In the third but not the first trimester, the mixture was positively associated with plasma total folate (12.0 nmol/L per one-quartile increase, 95% CI: 1.5, 22.7 nmol/L), negatively associated with %5MTHF (-2.8, 95% CI: -5.1,-0.70),and positively associated with %UMFA (13.4,95% CI: 4.4, 23.0).O3 was the primary component (weights ≥0.4).Associations were stronger for women with female fetuses. ConclusionAir pollution was positively associated with total folate concentrations and UMFA proportions and negatively associated with 5MTHF proportions.Associations were strongest in the third trimester and among pregnant women carrying female fetuses.Air pollution may influence maternal folate status during 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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 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".