Ambient air pollution concentrations and incidence of spontaneous abortion
Bibliographic record
Abstract
Background and aims: Previous epidemiologic studies suggest that air pollution exposure may be a risk factor for spontaneous abortion (SAB), i.e., pregnancy loss before 20 weeks’ gestation. However, most studies identified SABs from administrative records, which likely under-ascertain losses early in pregnancy. In a prospective preconception cohort study of couples trying to conceive, we examined the association between residential ambient air pollution concentrations and SAB incidence. Methods: Eligible female participants enrolled during 2013-2019. They were aged 21-45 years, residents of the United States or Canada, and trying to conceive without fertility treatments. Participants completed online questionnaires at enrollment, every 8 weeks during preconception, and about 8 weeks and 32 weeks of pregnancy. We restricted our analysis to the 5,513 participants who conceived within 12 cycles of follow-up. We estimated two-week average residential ambient concentrations of particulate matter <2.5 µm (PM2.5), nitrogen dioxide (NO2), and ozone (O3) using country-specific spatiotemporal models. We used Cox proportional hazards regression with gestational weeks as the time scale to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CI) for an interquartile range (IQR) increase in exposure, adjusting for individual- and neighborhood-level confounders. Results: 19% of participants reported a SAB during follow-up; of these, 72% were early losses (<8 weeks of gestation, median=6 weeks). Air pollution concentrations were not appreciably associated with SAB incidence. Among US participants, IRRs for a one-IQR increase in concentrations during the two weeks before conception were 1.08 (95% CI: 0.93-1.24) for PM2.5 (IQR=3.0 µg/m3), 1.02 (95% CI: 0.90-1.15) for NO2 (IQR=5.4 µg/m3), and 1.00 (95% CI: 0.86-1.17) for O3 (IQR=10.7 µg/m3). Associations were similar among Canadian participants, and among those reporting early losses. Conclusions: Air pollution concentrations showed little association with SAB incidence in this cohort of pregnancy planners. Keywords: air pollution, preconception cohort, pregnancy loss, spontaneous abortion
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.002 | 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 teacher head, 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".