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. 2022 Feb 28;1(1):e000053.
doi: 10.1136/bmjmed-2021-000053. eCollection 2022.

Severity of maternal infection and perinatal outcomes during periods of SARS-CoV-2 wildtype, alpha, and delta variant dominance in the UK: prospective cohort study

Nicola Vousden  1 , Rema Ramakrishnan  1 , Kathryn Bunch  1 , Eddie Morris  2 , Nigel A B Simpson  3 , Christopher Gale  4 , Patrick O'Brien  2   5 , Maria Quigley  1 , Peter Brocklehurst  6 , Jennifer J Kurinczuk  1 , Marian Knight  1
Affiliations

Severity of maternal infection and perinatal outcomes during periods of SARS-CoV-2 wildtype, alpha, and delta variant dominance in the UK: prospective cohort study

Nicola Vousden et al. BMJ Med. .

Abstract

Objective: To compare the severity of maternal infection and perinatal outcomes during periods in which wildtype, alpha variant, and delta variant of SARS-CoV-2 were dominant in the UK.

Design: Prospective cohort study.

Setting: 194 obstetric units across the UK, during the following periods: between 1 March and 30 November 2020 (wildtype dominance), between 1 December 2020 and 15 May 2021 (alpha variant dominance), and between 16 May and 31 October 2021 (delta variant dominance).

Participants: 4436 pregnant women admitted to hospital with covid-19 related symptoms.

Main outcome measures: Moderate to severe maternal SARS-CoV-2 infection (indicated by any of the following: oxygen saturation <95% on admission, need for oxygen treatment, evidence of pneumonia on imaging, admission to intensive care, or maternal death), and pregnancy and perinatal outcomes (including mode and gestation of birth, stillbirth, live birth, admission to neonatal intensive care, and neonatal death).

Results: 1387, 1613, and 1436 pregnant women were admitted to hospital with covid-19 related symptoms during the wildtype, alpha, and delta dominance periods, respectively; of these women, 340, 585, and 614 had moderate to severe infection, respectively. The proportion of pregnant women admitted with moderate to severe infection increased during the subsequent alpha and delta dominance periods, compared with the wildtype dominance period (wildtype 24.5% v alpha 36.2% (adjusted odds ratio 1.98, 95% confidence interval 1.66% to 2.37%); wildtype 24.5% v delta 42.8% (2.66, 2.21 to 3.20)). Compared with the wildtype dominance period, women admitted during the alpha dominance period were significantly more likely to have pneumonia, require respiratory support, and be admitted to intensive care; these three risks were even greater during the delta dominance period (wildtype v delta: pneumonia, adjusted odds ratio 2.52, 95% confidence interval 2.06 to 3.09; respiratory support, 1.90, 1.52 to 2.37; and intensive care, 2.71, 2.06 to 3.56). Of 1761 women whose vaccination status was known, 38 (2.2%) had one dose and 16 (1%) had two doses before their diagnosis (of whom 14 (88%) had mild infection). The proportion of women receiving drug treatment for SARS-CoV-2 management was low, but did increase between the wildtype dominance period and the alpha and delta dominance periods (10.4% wildtype v 14.9% alpha (2.74, 2.08 to 3.60); 10.4% wildtype v 13.6% delta (2.54, 1.90 to 3.38)).

Conclusions: While limited by the absence of variant sequencing data, these findings suggest that during the periods when the alpha and delta variants of SARS-CoV-2 were dominant, covid-19 was associated with more severe maternal infection and worse pregnancy outcomes than during the wildtype dominance period. Most women admitted with SARS-CoV-2 related symptoms were unvaccinated. Urgent action to prioritise vaccine uptake in pregnancy is essential.

Study registration: ISRCTN40092247.

Keywords: COVID-19; neonatology; pregnancy complications.

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Conflict of interest statement

Competing interests: Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: MK, MQ, PB, PO’B, and JJK received grants from the NIHR in relation to the submitted work; KB, NV, and NABS declare no conflicts of interest; EM is trustee of the Royal College of Obstetricians and Gynaecologists and British Menopause Society, and new chair of the board of trustees for Group B Strep Support; CG was financially supported by UK Medical Research Council (MRC)through a clinician scientist fellowship; PB was past chair of the MRC/NIHR Methodology Research Programme panel with previous grant funding from MRC, NIHR, and the Welcome Trust, and provides consultancy services for personal fees to AG Biotest.

Figures

Figure 1
Figure 1
Visual abstract
Figure 2
Figure 2
Admissions of pregnant women with symptoms of confirmed SARS-CoV-2 to UK hospitals during dominance periods of original wildtype (1 March to 30 November 2020), alpha variant (1 December 2020 to 15 May 2021), and delta variant (16 May to 31 October 2021)
See this image and copyright information in PMC

References

    1. Allotey J, Stallings E, Bonet M. Clinical manifestations, risk factors, and maternal and perinatal outcomes of coronavirus disease 2019 in pregnancy: living systematic review and meta-analysis. BMJ 2020;370:m3320. 10.1136/bmj.m3320 - DOI - PMC - PubMed
    1. World Health Organisation . Tracking SARS-CoV-2 variants. Geneva: World Health Organisation, 2021. https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/
    1. Public Health England . SARS-CoV-2 variants of concern and variants under investigation in England: technical Briefing 13. London: Public Health England, 2021.
    1. Cevik M, Mishra S. SARS-CoV-2 variants and considerations of inferring causality on disease severity. Lancet Infect Dis 2021;21:1472–4. 10.1016/S1473-3099(21)00338-8 - DOI - PMC - PubMed
    1. Sheikh A, McMenamin J, Taylor B, et al. . SARS-CoV-2 delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet 2021;397:2461–2. 10.1016/S0140-6736(21)01358-1 - DOI - PMC - PubMed