Evidence map›Paper›PMID 33741725›Full record

SynthesisCMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne2021

The impact of COVID-19 on pregnancy outcomes: a systematic review and meta-analysis.

Shu Qin Wei, Marianne Bilodeau-Bertrand, Shiliang Liu, Nathalie Auger

Open access · goldAbstract readMeta-AnalysisSystematic Review
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 469 papers, 6 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
469citing papers in PubMed, 6 pooled it
123.5field-weighted citation impact, top 1% of its field
1 · What the graph read from it

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.

2 · The registry

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.

3 · Its place in the literature

Who cites it

469 citing papers in PubMed, 6 syntheses or guidelines pooled it, 908 citations in OpenAlex.

  1. Adverse outcomes among pregnant women with COVID-19 according to hospitalization status: A prospective individual participant data meta-analysis in Europe and North America.International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics · 2026
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  6. Neonatal and maternal outcomes of mRNA versus Non-mRNA COVID-19 vaccines in pregnant patients: a systematic review and meta-analysis.Revista brasileira de ginecologia e obstetricia : revista da Federacao Brasileira das Sociedades de Ginecologia e Obstetricia · 2024
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  11. Right-sizing Incentives.Journal of development economics · 2026
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409 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

4 authors at 2 institutions in 1 country.

Shu Qin WeiDepartment of Obstetrics and Gynecology (Wei), Centre hospitalier universitaire Sainte-Justine; Centre de recherche du Centre hospitalier de l'Université de Montréal, Department of Social and Preventive Medicine (Auger), School of Public Health, Université de Montréal; Bureau d'information et d'études en santé des populations (Wei, Bilodeau-Bertrand, Auger), Institut national de santé publique du Québec, Montréal, Que.; Centre for Surveillance and Applied Research (Liu), Public Health Agency of Canada, Ottawa, Ont.
Marianne Bilodeau-BertrandDepartment of Obstetrics and Gynecology (Wei), Centre hospitalier universitaire Sainte-Justine; Centre de recherche du Centre hospitalier de l'Université de Montréal, Department of Social and Preventive Medicine (Auger), School of Public Health, Université de Montréal; Bureau d'information et d'études en santé des populations (Wei, Bilodeau-Bertrand, Auger), Institut national de santé publique du Québec, Montréal, Que.; Centre for Surveillance and Applied Research (Liu), Public Health Agency of Canada, Ottawa, Ont.
Shiliang LiuDepartment of Obstetrics and Gynecology (Wei), Centre hospitalier universitaire Sainte-Justine; Centre de recherche du Centre hospitalier de l'Université de Montréal, Department of Social and Preventive Medicine (Auger), School of Public Health, Université de Montréal; Bureau d'information et d'études en santé des populations (Wei, Bilodeau-Bertrand, Auger), Institut national de santé publique du Québec, Montréal, Que.; Centre for Surveillance and Applied Research (Liu), Public Health Agency of Canada, Ottawa, Ont.
Nathalie AugerDepartment of Obstetrics and Gynecology (Wei), Centre hospitalier universitaire Sainte-Justine; Centre de recherche du Centre hospitalier de l'Université de Montréal, Department of Social and Preventive Medicine (Auger), School of Public Health, Université de Montréal; Bureau d'information et d'études en santé des populations (Wei, Bilodeau-Bertrand, Auger), Institut national de santé publique du Québec, Montréal, Que.; Centre for Surveillance and Applied Research (Liu), Public Health Agency of Canada, Ottawa, Ont. nathalie.auger@inspq.qc.ca.
Centre Hospitalier Universitaire Sainte-Justine · CACentre Hospitalier de l’Université de Montréal · CA

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThe impact of coronavirus disease 2019 (COVID-19) on maternal and newborn health is unclear. We aimed to evaluate the association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy and adverse pregnancy outcomes.

methodsWe conducted a systematic review and meta-analysis of observational studies with comparison data on SARS-CoV-2 infection and severity of COVID-19 during pregnancy. We searched for eligible studies in MEDLINE, Embase, ClinicalTrials.gov, medRxiv and Cochrane databases up to Jan. 29, 2021, using Medical Subject Headings terms and keywords for "severe acute respiratory syndrome coronavirus 2 OR SARS-CoV-2 OR coronavirus disease 2019 OR COVID-19" AND "pregnancy." We evaluated the methodologic quality of all included studies using the Newcastle-Ottawa Scale. Our primary outcomes were preeclampsia and preterm birth. Secondary outcomes included stillbirth, gestational diabetes and other pregnancy outcomes. We calculated summary odds ratios (ORs) or weighted mean differences with 95% confidence intervals (CI) using random-effects meta-analysis.

resultsWe included 42 studies involving 438 548 people who were pregnant. Compared with no SARS-CoV-2 infection in pregnancy, COVID-19 was associated with preeclampsia (OR 1.33, 95% CI 1.03 to 1.73), preterm birth (OR 1.82, 95% CI 1.38 to 2.39) and stillbirth (OR 2.11, 95% CI 1.14 to 3.90). Compared with mild COVID-19, severe COVID-19 was strongly associated with preeclampsia (OR 4.16, 95% CI 1.55 to 11.15), preterm birth (OR 4.29, 95% CI 2.41 to 7.63), gestational diabetes (OR 1.99, 95% CI 1.09 to 3.64) and low birth weight (OR 1.89, 95% CI 1.14 to 3.12).

interpretationCOVID-19 may be associated with increased risks of preeclampsia, preterm birth and other adverse pregnancy outcomes.

Indexed as

SARS-CoV-2COVID-19Diabetes, GestationalFemaleHumansInfant, Low Birth WeightInfant, NewbornInfectious Disease Transmission, VerticalObservational Studies as TopicPre-EclampsiaPregnancyPregnancy Complications, InfectiousPregnancy OutcomePremature BirthStillbirth

Identifiers

PMID33741725
PMCPMC8084555
OpenAlexW3138907726

What OpenQuestion holds

Textmetadata
LicenceCC BY-NC-ND
Read underepoch 390

Registered trials

None linked

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.