Cross-Sectional, Prospective Cohort
Study population and setting
This study, which included a prospective cohort and a cross-sectional survey to replicate cohort findings, assessed SARS-CoV-2 severity in reproductive age women (18-44 years old) who reported their pregnancy status from March to June 2020. The prospective cohort included women from the United States, United Kingdom, and Sweden (400,750 women in total) who used a smartphone application for a median of 18 days (Interquartile Range: 6, 34) between March 24 and June 7, 2020 to record symptoms associated with COVID-19. The cross-sectional replication dataset included 1,344,996 women surveyed through Facebook (participants were selected via a sampling procedure designed to achieve a representative sample of Facebook’s United States active user base), which asked about COVID-19 symptoms in the preceding 24 hours between April 6 and June 7, 2020. Participants in both prospective and cross-sectional samples were classified based on self-report according to their pregnancy status (pregnant vs. not pregnant), SARS-CoV-2 test results, COVID-19 symptoms, and hospitalization status. They used a bootstrapped train-test procedure in the prospective cohort to classify non-pregnant participants who declined to report their test results as suspected test positive based on self-reported symptoms. They assessed for differences in reported symptoms among women by pregnancy status, test positivity, and hospitalization status in both datasets. Finally, they created a severity index among hospitalized participants that was a weighted sum of symptoms present at hospital presentation.
Summary of Main Findings
In the prospective cohort, 14,049 (3.5%) of the 400,750 participants reported they were pregnant. While pregnant women were more likely to be tested (8% versus 6.1%), there were similar percentages of positive tests in pregnant and non-pregnant women (0.6% and 0.7%, respectively), positive tests and hospitalizations (0.07% and 0.09%, respectively), and suspected positive tests and hospitalizations (0.15% and 0.16%, respectively). Finally, non-pregnant women (6.7%) were more likely to have symptoms that classified them as suspected positive cases than pregnant women (4.5%). This pattern held in the cross-sectional replication dataset in receipt of testing (2.7% of pregnant women, 2.4% in non-pregnant women), and test positivity (0.4% for both groups), suspected positives (3% of pregnant women, 4% in non-pregnant women), which included 41,796 (3.1%) pregnant women of 1,344,966 participants. In the cross-sectional replication dataset, hospitalized pregnant women were more likely to report positive tests (0.09%) than hospitalized non-pregnant women (0.03% and 0.12%). Hospitalized pregnant women with COVID-19 were more likely to report abdominal pain and less likely to report delirium and skipped meals than hospitalized non-pregnant women with COVID-19 in both cohorts. Non-hospitalized pregnant women were less likely to report diarrhea than non-hospitalized non-pregnant women in both cohorts. Finally, symptom severity scores among hospitalized participants were not statistically different by pregnancy status in either cohort.
This study employed large sample sizes and included participants in several countries.
Both arms likely recruited participants who are more health conscious than the general population and are likely healthier and potentially at lower risk of adverse COVID-19 sequelae because of their baseline health status and therefore not representative to all women of reproductive age. Data from lower income women or other women who are less digitally connected are not represented; if their results differ due to underlying comorbidities that may affect COVID-19 severity, these results may not fully generalize to all pregnant women. Furthermore, the symptom severity score is difficult to interpret outside of the context of this study. It is also difficult to comment on whether differences in reported hospitalizations among pregnant and non-pregnant women was due to increased concern among physicians (who might be more likely to admit pregnant women with COVID-19) or concerning differences in vital signs or laboratory values.
This study included a large sample of women, including a substantial number of pregnant women, demonstrating the potential of using smartphone applications and social media to conduct broad-based symptom tracking during a pandemic and trying to understand COVID-19 severity in pregnant women.
This review was posted on: 22 April 2021