Exposure to Computed Tomography Before Pregnancy and Risk for Pregnancy Loss and Congenital Anomalies
Bibliographic record
Abstract
BACKGROUND: Animal studies show ovarian follicle damage and mutagenesis after ionizing radiation exposure. Computed tomography (CT) imaging is commonly done outside pregnancy, but risks to future pregnancy are unknown. OBJECTIVE: To evaluate the risk for spontaneous pregnancy loss and congenital anomalies in offspring of women exposed to CT ionizing radiation before conception. DESIGN: Population-based observational study. SETTING: Ontario, Canada. PARTICIPANTS: 5 142 339 recognized pregnancies and 3 451 968 live births identified between 1992 and 2023. MEASUREMENTS: The exposure was the cumulative number of CT scans up to 4 weeks before conception. Outcomes were spontaneous pregnancy loss (miscarriage, ectopic pregnancy, or stillbirth) among recognized pregnancies and congenital anomalies diagnosed within the first year of life among live births. RESULTS: Mean maternal age was 29 years. Diabetes, hypertension, obesity, and smoking were more common in those exposed to CT imaging. Among recognized pregnancies, rates of spontaneous pregnancy loss were 101, 117, 130, and 142 per 1000 pregnancies with 0, 1, 2, and 3 or more preconception CT scans, respectively, and adjusted hazard ratios (aHRs) were 1.08 (95% CI, 1.07 to 1.08) for 1 CT scan, 1.14 (CI, 1.12 to 1.16) for 2 CT scans, and 1.19 (CI, 1.16 to 1.21) for 3 or more CT scans. Among live births, rates of congenital anomalies were 62, 84, 96, and 105 per 1000 births in those with 0, 1, 2, and 3 or more CT scans, and aHRs were 1.06 (CI, 1.05 to 1.08) for 1 CT scan, 1.11 (CI, 1.09 to 1.14) for 2 CT scans, and 1.15 (CI, 1.11 to 1.18) for 3 or more CT scans. The risk observed with head CT was not consistently lower than with CT of the abdomen, pelvis, or lower spine. LIMITATION: Incomplete ascertainment of CT exposure and underlying indication may have contributed to residual confounding. CONCLUSION: Exposure to preconception CT imaging may be associated with higher risks for spontaneous pregnancy loss and congenital anomalies, but causal mechanisms remain to be elucidated. Alternative imaging methods should be considered when appropriate. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research.
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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) | 0.000 | 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".