Volume 129, Issue 2 p. 221-231
Research Article
Free to Read

SARS-CoV-2 infection among hospitalised pregnant women and impact of different viral strains on COVID-19 severity in Italy: a national prospective population-based cohort study

S Donati

S Donati

National Centre for Disease Prevention and Health Promotion, Istituto Superiore di Sanità – Italian National Institute of Health, Rome, Italy

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E Corsi

Corresponding Author

E Corsi

National Centre for Disease Prevention and Health Promotion, Istituto Superiore di Sanità – Italian National Institute of Health, Rome, Italy

Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy

Correspondence: E Corsi, National Centre for Disease Prevention and Health Promotion, Istituto Superiore di Sanità – Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy. Email: [email protected]

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A Maraschini

A Maraschini

Servizio tecnico scientifico di statistica, Istituto Superiore di Sanità – Italian National Institute of Health, Rome, Italy

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MA Salvatore

MA Salvatore

National Centre for Disease Prevention and Health Promotion, Istituto Superiore di Sanità – Italian National Institute of Health, Rome, Italy

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the ItOSS-COVID-19 Working Group

the ItOSS-COVID-19 Working Group

The members of the ItOSS COVID-19 Working Group are listed in Appendix  A

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First published: 23 October 2021
Citations: 36

Abstract

Objective

The primary aim of this article was to describe SARS-CoV-2 infection among pregnant women during the wild-type and Alpha-variant periods in Italy. The secondary aim was to compare the impact of the virus variants on the severity of maternal and perinatal outcomes.

Design

National population-based prospective cohort study.

Setting

A total of 315 Italian maternity hospitals.

Sample

A cohort of 3306 women with SARS-CoV-2 infection confirmed within 7 days of hospital admission.

Methods

Cases were prospectively reported by trained clinicians for each participating maternity unit. Data were described by univariate and multivariate analyses.

Main outcome measures

COVID-19 pneumonia, ventilatory support, intensive care unit (ICU) admission, mode of delivery, preterm birth, stillbirth, and maternal and neonatal mortality.

Results

We found that 64.3% of the cohort was asymptomatic, 12.8% developed COVID-19 pneumonia and 3.3% required ventilatory support and/or ICU admission. Maternal age of 30–34 years (OR 1.43, 95% CI 1.09–1.87) and ≥35 years (OR 1.62, 95% CI 1.23–2.13), citizenship of countries with high migration pressure (OR 1.75, 95% CI 1.36–2.25), previous comorbidities (OR 1.49, 95% CI 1.13–1.98) and obesity (OR 1.72, 95% CI 1.29–2.27) were all associated with a higher occurrence of pneumonia. The preterm birth rate was 11.1%. In comparison with the pre-pandemic period, stillbirths and maternal and neonatal deaths remained stable. The need for ventilatory support and/or ICU admission among women with pneumonia increased during the Alpha-variant period compared with the wild-type period (OR 3.24, 95% CI 1.99–5.28).

Conclusions

Our results are consistent with a low risk of severe COVID-19 disease among pregnant women and with rare adverse perinatal outcomes. During the Alpha-variant period there was a significant increase of severe COVID-19 illness. Further research is needed to describe the impact of different SARS-CoV-2 viral strains on maternal and perinatal outcomes.