<scp>COVID</scp>‐19 vaccination around the time of conception and risk of placenta‐mediated adverse pregnancy outcomes
Bibliographic record
Abstract
INTRODUCTION: Although numerous studies have documented no association between COVID-19 vaccination during pregnancy and maternal and fetal health outcomes, fewer studies have evaluated fetal health effects after COVID-19 vaccination around the time of conception and early pregnancy, a time when maternal exposures may affect early placentation and the subsequent risk of placenta-mediated adverse pregnancy outcomes. MATERIAL AND METHODS: We used province-wide databases in Ontario to conduct a population-based cohort study including all live and stillbirths ≥20 weeks' gestation with a last menstrual period (LMP) between April 1 and December 31, 2021. We deterministically linked birth registry data to the vaccine registry for all 80 253 eligible pregnancies; 31 209 (38.9%) received ≥1 dose of the COVID-19 vaccine around the time of conception or first trimester. Using Cox regression, we estimated propensity score weighted hazard ratios (aHR) and 95% confidence intervals (CI) for associations between ≥1 dose of mRNA COVID-19 vaccine during the periconceptional/first trimester exposure window (28 days before the LMP to the end of first trimester) and study outcomes: hypertensive disorders (gestational hypertension, preeclampsia, eclampsia), placental abruption, preterm birth (<37 weeks), small-for-gestational-age (SGA) birth (<10th percentile), and stillbirth. RESULTS: COVID-19 vaccination around the time of conception or first trimester was associated with a small increased risk of hypertensive disorders in pregnancy in exposed versus unexposed individuals (7.4% vs. 6.1%; aHR: 1.10, 95% CI: 1.03-1.17), mostly attributed to gestational hypertension (5.0% vs. 4.1%; aHR 1.13, 95% CI: 1.05-1.22). There was no increased risk of preeclampsia (1.8% vs. 1.5%; aHR 1.08, 95% CI: 0.95-1.22), eclampsia (0.1% vs. 0.1%; aHR: 1.12, 95% CI 0.65-1.95), placental abruption (0.8% vs. 1.0%; aHR: 0.77, 95%CI: 0.65-0.91), preterm birth (8.0% vs. 8.9%; aHR: 0.92, 95%CI: 0.87-0.97), SGA birth (8.9% vs. 9.3%; aHR: 1.00, 95%CI: 0.95-1.06), or stillbirth (0.4% vs. 0.6%; aHR: 0.66, 95%CI: 0.52-0.82). CONCLUSIONS: This population-based Canadian study provides additional evidence evaluating COVID-19 vaccine administration around the start of pregnancy. While we identified no association with most placenta-mediated outcomes, we report a slight increase in the rate of gestational hypertension. This could be a true association or attributed to residual confounding. Further research is needed to verify.
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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 | 0.001 | 0.043 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| 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".