ArticleActa obstetricia et gynecologica Scandinavica2025
COVID-19 vaccination around the time of conception and risk of placenta-mediated adverse pregnancy outcomes.
Article in Acta obstetricia et gynecologica Scandinavica, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
3 citing papers in PubMed.
- Role of microbial metabolites in the pathogenesis of hypertensive disorders of pregnancy: From short‑chain fatty acids to tryptophan metabolites (Review).Molecular medicine reports · 2026Review
- COVID-19 vaccination during or just prior to pregnancy and hypertensive disorders of pregnancy.Vaccine · 2026Article
- COVID-19 vaccination around the time of conception and risk of placenta-mediated adverse pregnancy outcomes.Acta obstetricia et gynecologica Scandinavica · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
22 authors.
Funding
Abstract
introductionAlthough 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
methodsWe 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.
resultsCOVID-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).
conclusionsThis 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.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.