key: cord-0879951-81zhhpz2
authors: Engjom, Hilde; Aabakke, Anna J.M.; Klungsøyr, Kari; Svanvik, Teresia; Äyräs, Outi; Jonasdottir, Eva; Thurn, Lars; Jones, Elin; Pettersson, Karin; Nyfløt, Lill T.; Al‐Zirqi, Iqbal; Vangen, Siri; Júlíusson, Pétur B.; Källén, Karin; Gissler, Mika; Krebs, Lone
title: COVID‐19 in pregnancy—characteristics and outcomes of pregnant women admitted to hospital because of SARS‐CoV‐2 infection in the Nordic countries
date: 2021-05-07
journal: Acta Obstet Gynecol Scand
DOI: 10.1111/aogs.14160
sha: 0ad77f76913a85401818e07a230c81bbe0573705
doc_id: 879951
cord_uid: 81zhhpz2

INTRODUCTION: Population‐based studies about the consequences of SARS‐CoV‐2 infection (COVID‐19) in pregnancy are few and have limited generalizability to the Nordic population and healthcare systems. MATERIAL AND METHODS: This study examines pregnant women with COVID‐19 in the five Nordic countries. Pregnant women were included if they were admitted to hospital between 1 March and 30 June 2020 and had a positive SARS‐CoV‐2 PCR test ≤14 days prior to admission. Cause of admission was classified as obstetric or COVID‐19‐related. RESULTS: In the study areas, 214 pregnant women with a positive test were admitted to hospital, of which 56 women required hospital care due to COVID‐19. The risk of admission due to COVID‐19 was 0.4/1000 deliveries in Denmark, Finland and Norway, and 3.8/1000 deliveries in the Swedish regions. Women hospitalized because of COVID‐19 were more frequently obese (p < 0.001) and had a migrant background (p < 0.001) compared with the total population of women who delivered in 2018. Twelve women (21.4%) needed intensive care. Among the 56 women admitted due to COVID‐19, 48 women delivered 51 infants. Preterm delivery (n = 12, 25%, p < 0.001) and cesarean delivery (n = 21, 43.8%, p < 0.001) were more frequent in women with COVID‐19 compared with women who delivered in 2018. No maternal deaths, stillbirths or neonatal deaths were reported. CONCLUSIONS: The risk of admission due to COVID‐19 disease in pregnancy was low in the Nordic countries. A fifth of the women required intensive care and we observed higher rates of preterm and cesarean deliveries. National public health policies appear to have had an impact on the risk of admission due to severe COVID‐19 disease in pregnancy. Nordic collaboration is important in collecting robust data and assessing rare outcomes.

The World Health Organization declared a global pandemic of coronavirus disease in March 2020. 1 During the H1N1 influenza pandemic, pregnant women were particularly vulnerable, resulting in increases of maternal and perinatal mortality among those infected. [2] [3] [4] [5] [6] [7] [8] Systematic review and meta-analysis by WHO about the effect of COVID-19 in pregnancy identified preexisting comorbidities and high maternal age and body mass index (BMI) as risk factors for severe infection. 9 Preterm birth rate increased among infected women. 9 Recent publications from the USA indicate that pregnant women are at higher risk for serious COVID-19 disease compared with non-pregnant women. 10, 11 These studies and the majority of studies in the WHO systematic review were performed in settings with limited generalizability to the Nordic populations and healthcare systems. With the on-going pandemic, populationbased studies with larger case numbers and lower risk of bias are crucial for guiding disease surveillance and health management. 12 A few population-based studies assessing the risk and consequences of COVID-19 infection in pregnancy have been published. [13] [14] [15] However, the inclusion criteria comprised all causes of hospital admission, resulting in heterogeneous study populations.

The population in the Nordic countries is relatively uniform, and healthcare during pregnancy is provided free of charge. All five countries have medical birth registries with mandatory registrations of maternal and fetal/neonatal outcomes of all births.

The objective of this study was to describe hospital admissions of pregnant women with COVID-19 in the Nordic countries. We present preliminary, aggregated results including the characteristics and medical risk factors, clinical management and outcomes of pregnant women with COVID-19, focusing primarily on the group of women admitted due to COVID-19, during the first 4 months of the pandemic in the Nordic countries. Due to different national and regional testing strategies (Table S1) the study groups in the various countries were heterogeneous, with more women with asymptomatic/mild COVID-19 admitted for delivery or obstetric care in countries/regions with universal screening. Characteristics of women admitted for any reason are shown in Table S2 . We therefore restricted further analyses to the pregnant women who required hospital admission because of COVID-19 disease, as shown in the flowchart (Figure 1 ).

disease. There were no admissions in Iceland and the risk of hospital admission was 0.4/1000 deliveries (range 0.3-0.5) in Denmark, Finland and Norway, and 3.8/1000 in the Swedish regions. Figure 2 illustrates the gestational age at first positive SARS-CoV-2 test among the included women. Most women admitted due to COVID-19 were in the third trimester of pregnancy when they tested positive. Figure S2 shows the month of first positive test and thus illustrates the pandemic timeline.

Characteristics of the pregnant women admitted due to COVID-19 are presented together with the Medical Birth Registry data from 2018 in Table 1 . Compared with the women who delivered in 2018, women admitted due to COVID-19 were more frequently obese, had BMI >30 (p < 0.001) and were migrants (p < 0.001).

In the Swedish regions, relatively more women admitted due Induction of labor, preterm delivery, CD and emergency CD were more frequent among women admitted due to COVID-19 compared with the 2018 birth population, which corresponds to previous findings. 9,13,23 An increasing risk of preterm delivery and CD with increasing severity of COVID-19 has also been reported. 14 We did not have concurrent data for non-infected pregnancies available for comparison at the time of publication. We therefore relate the results to 2018 data not influenced by the pandemic, which may be viewed as an advantage. However, the NOSS COVID-19 group plans to analyze data against population data for 2020 when it In Denmark we would like to thank the reporting clinicians at the Danish units (in alphabetical order): Eva K. Andersen, Charlotte

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All authors participated in the joint study planning and in planning and implementing their respective national data collection. HE, AA, TS, EJ and OÄ summarized the national datasets. HE, AA and KK analyzed the data. HE and AA drafted the manuscript and amended it according to feedback from all authors.