SARS-CoV-2 Infection During Pregnancy—An Analysis of Clinical Data From Germany and Austria From the CRONOS Registry

Abstract

Background: Using data from the German CRONOS registry, we assessed the risk of a complicated course of COVID-19 in women with a SARS-CoV-2-infection during pregnancy, with particular consideration of gestational age, vaccination status, and pandemic dynamics.

Methods: Data acquired in two separate periods (March 2020 to August 2021; January to June 2022) for CRONOS, a prospective, hospital-based observational study (DRKS00021208), were studied with logistic regression models. Odds ratios comparing 32 with 22 weeks of gestation were calculated for relevant COVID-19-specific events occurring within 4 weeks of a positive test result.

Results: Data from 3481 women were evaluated. The risk of all of the defined COVID-19-specific events was low among women who became ill with COVID-19 during the first trimester and rose with increasing gestational age into the early third trimester. For example, the odds ratio for hospitalization because of a COVID-19 infection, comparing 32 versus 22 weeks of gestation, was 1.4 (95% confidence interval [1.2; 1.7]). This risk was lower in the second period of data acquisition than in the first (OR 0.66; 95% CI [0.50; 0.88]), and it was even lower if the pregnant patient had been vaccinated against COVID-19 (OR 0.27; 95% CI [0.18; 0.41]).

Conclusion: These findings can serve as a basis for counseling about prophylactic or therapeutic measures, such as the administration of monoclonal antibodies. They underscore the efficacy of vaccination for pregnant women even during the omicron phase of the pandemic.

Figure 1

The probability (y-axis) of different COVID-19-related events after a positive SARS-CoV-2 test result at defined gestational ages (GA in weeks; x-axis) among the group of 1827 patients with COVID-19 from period 1 (infection between beginning of pandemic and 24 August 2021), showing in each case the regression line (unbroken line) and the 95% confidence intervals (dotted lines; based on logistic regression with restricted cubic spline terms) a) COVID-19-related hospitalization within 4 weeks of positive test result b) Pneumonia and/or oxygen therapy c) Transfer to intensive care unit d) Invasive ventilation e) COVID-19-related delivery within 4 weeks of positive test result

Figure 2

The probability of a perinatal event (y-axis) of a perinatal event after a positive SARS-CoV-2 test result at defined gestational ages (GA in weeks; x-axis) among the group of 1497 symptomatic patients from period 1 (infection between beginning of pandemic and 24 August 2021), for whom data on the outcome of pregnancy were available at the time of data freezing, showing in each case the regression line (unbroken line) and the 95% confidence intervals (dotted lines; based on logistic regression with restricted cubic spline terms) a) Premature ending of pregnancy within 4 weeks of positive SARS-CoV-2 test result up to a maximum GA of 36 + 6 weeks b) Ending of pregnancy within 4 weeks of infection followed by transfer of the neonate to a neonatal intensive care unit (NICU), or antenatal or postnatal death of the child

eFigure 1

Flowchart of the processing of the data from period 1, showing the underlying inclusion and exclusion criteria

eFigure 2

The number of SARS-CoV-2-positive pregnant women in the cohort from data collection period 1 (y-axis) by gestational age in weeks (GA) at the time of the positive test result (x-axis). Black bars, women with COVID-19; gray bars, asymptomatic women. Note the continuous rise in the number of women with COVID-19 with increasing GA. However, asymptomatic women are over-represented after GA 37 weeks. These “incidental COVIDs” were mostly detected on screening after hospitalization for delivery.

eFigure 3

Flowchart of the data selection, showing the underlying inclusion and exclusion criteria, for the comparison of periods 1 and 2 taking account of vaccination status