key: cord-0924444-b5iy7pf9
authors: Kodde, Cathrin; Bonsignore, Marzia; Hohenstein, Sven; Kuhlen, Ralf; Meier-Hellmann, Andreas; Bollmann, Andreas; Nachtigall, Irit
title: Outcomes and proportions of pregnant females during the first and consecutively waves of COVID-19: observational cohort study
date: 2021-09-08
journal: Clin Microbiol Infect
DOI: 10.1016/j.cmi.2021.09.002
sha: 21e58848af8c64f59aa23202fc184a520faa4507
doc_id: 924444
cord_uid: b5iy7pf9

OBJECTIVES: It has been suggested that pregnant females were affected more severely during the late, as opposed to the early wave of the COVID-19 pandemic. The aim of our study was to compare the proportion of pregnant females among hospitalized females in childbearing age, their rate of intensive care (ICU) admission, need for mechanical ventilation and mortality during the waves. METHODS: The study is a retrospective analysis of claims data on females in childbearing age (16 – 49y) admitted to 76 hospitals with a lab-confirmed SARS-CoV-2 infection. The observation period was divided into first (March 7(th), 2020-September 30(th), 2020) and second wave (October 1(st) - April 17(th), 2021). Comorbidities derived from claims data were summarized in the Elixhauser Comorbidity Index (ECI). RESULTS: 1,879 females were included, 532 of whom were pregnant. During the second wave, the proportion of pregnant females was higher (29.3% (484/1,650) vs. 21.0% (48/229), p<.01), they were older (mean ± standard deviation SD = 29.1±5.9 y vs. 27±6.3 y, p=.02 in the first wave) and had comparable comorbidities (ECI mean±SD=0.3±3.5 vs.–0.2±2.0 p=.30). 6.2% (3/48) of pregnant females were admitted to ICU during the first wave vs. 3.3% (16/484) during the second wave (odds ratio OR=0.51, 95% confidence interval CI=0.14–1.83, p=.30). 2.1% (1/48) were ventilated vs. 1.2% (6/484, OR=0.60, 95% CI=0.07–5.23, p=.64). No deaths were observed among the hospitalized pregnant females in either wave. CONCLUSIONS: Proportionally more pregnant females with COVID-19 were hospitalized in the second wave compared to the first wave but no more severe outcomes were registered.

Objectives:

It has been suggested that pregnant females were affected more severely during the late, as opposed to the early wave of the COVID-19 pandemic. The aim of our study was to compare the proportion of pregnant females among hospitalized females in childbearing age, their rate of intensive care (ICU) admission, need for mechanical ventilation and mortality during the waves.

The study is a retrospective analysis of claims data on females in childbearing age (16 -49y) admitted to 76 hospitals with a lab-confirmed SARS-CoV-2 infection. The observation period was divided into first (March 7 th , 2020-September 30 th , 2020) and second wave (October 1 st -April 17 th , 2021). Comorbidities derived from claims data were summarized in the Elixhauser Comorbidity Index (ECI).

1,879 females were included, 532 of whom were pregnant. During the second wave, the proportion of pregnant females was higher (29.3% (484/1,650) vs. 21.0% (48/229), p<.01), they were older (mean ± standard deviation SD = 29.1±5.9y vs. 27±6.3y, p=.02 in the first wave) and had comparable comorbidities (ECI mean±SD=0.3±3.5 vs.-0.2±2.0 p=.30).

6.2% (3/48) of pregnant females were admitted to ICU during the first wave vs. 3.3%

From first appearance of COVID-19 there were concerns that infection might affect pregnant females more severely with a high risk of intensive care unit (ICU) admission and death (1) . During the first wave of the COVID-19 pandemic few pregnant females were infected. This changed during second wave when infection rates increased, especially in Europe. Some recent studies reported that proportionally more pregnant females with COVID-19 were hospitalized (2) or referred for extracorporeal membrane

The aim of our study was to compare pregnant females with COVID-19 as a proportion of all females in childbearing age hospitalized with COVID-19 during the different waves, their rate of intensive care (ICU) admission, mechanical ventilation, and mortality rates.

The research was conducted as an observational retrospective cohort study. We summer 2020. For our analysis, we therefore defined October 1 st , 2020 as cut-off between first and second wave and summarized data from second and third wave.

Claims data on comorbidities were summarized in the Elixhauser Comorbidity Index (4) .

Inferential statistics were based on generalized linear mixed models (GLMM) specifying hospitals as random factor (5). We employed Poisson GLMMs for count data. Effects were estimated with the lme4 package (6) in R (version 4.0.2). In all models, we specified varying intercepts for the random factor. For the comparison of treatments and outcomes, we used logistic GLMMs. For all tests, we apply a two-tailed 5% error criterion for significance.

For description of characteristics of cohorts' patients, we employed χ2-tests for binary variables and analysis of variance for numeric variables. For weighted Elixhauser comorbidity index, AHRQ algorithm was applied (7).

Local Ethics Committee (vote: AZ490/20-ek) and Helios Kliniken GmbH data protection authority approved data use for this study.

A total number of 1,879 females in childbearing age were hospitalized and tested positive for SARS-CoV-2, 532 (28.3%) of whom were pregnant. Pregnant females were significantly younger (mean±standard deviation: 28.9±5.9 years (y) vs. 37.3±9.3 y, p=<.01) and had significantly fewer comorbidities than non-pregnant females (ECI=0.2 vs. 3.0, p<.01), including pregnancy-associated obesity (5.8% (31/532) vs.

14.8% (199/1,347), p<.01) (table 1).

We saw an expected rise in total number of SARS-CoV-2 positive females admitted to the hospital in the second wave, concordantly to higher infection rates in the general For non-pregnant females, no difference in age and comorbidities was observed. Out of 48 pregnant females, three (6.2%) were admitted to ICU during the first wave versus 16/484 in the second wave (3.3%, odds ratio OR=0.51, 95% CI=0.14-1.83, p=.30). We found no difference in the odds ratio for ICU admission and mechanical ventilation between the two waves. In total, ICU and ventilation were rare among pregnant females, which does not allow further analyses. No COVID-19 related death among pregnant females was observed, whereas previous studies have shown mortality rates ranging from 0.8% to 1.6% (3, 11, 12) . A higher ICU admission rate of pregnant females during the British second wave was documented (13), without reporting whether this difference was statistically significant. Another research described a significant increase of pregnant females among all females in childbearing age referred for extracorporeal membrane oxygenation (ECMO) (3). These findings suggest a more severe course in the second wave, but it could also have been partially caused by an increase in the overall numbers of pregnancies as was observed in England and Wales (14).

A major limitation of our study is that we could not compare the outcome of infected pregnant females to non-pregnant females: to sufficiently control for biases (e.g. the admission with vs. because of COVID-19) a matched pair analysis would be required, which was not possible with our data.

In conclusion, we observed an increase of proportion of pregnant females among hospitalized females with COVID-19 that may be partially due to the higher pregnancy rate in the whole population. Our data do not confirm the previous described trend that pregnant females experienced a worse outcome of COVID-19 infection during the second wave.

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