# SARS-CoV-2 Infection and Adverse Maternal and Perinatal Outcomes: Time-to-Event Analysis of a Hospital-Based Cohort Study of Pregnant Women in Rio de Janeiro, Brazil

## TL;DR

This study finds that SARS-CoV-2 infection during pregnancy increases the risk of severe maternal outcomes but does not strongly affect perinatal outcomes.

## Contribution

The study provides new evidence on the association between SARS-CoV-2 infection during pregnancy and maternal outcomes in a hospital-based cohort in Brazil.

## Key findings

- SARS-CoV-2 infected pregnant women had a significantly higher risk of adverse maternal outcomes compared to uninfected women.
- Vertical transmission of SARS-CoV-2 was observed in 3.6% of tested neonates.
- Preterm deliveries were more common among infected women, but survival analysis showed no significant effect on perinatal outcomes.

## Abstract

Understanding perinatal health outcomes following SARS-CoV-2 infection during pregnancy necessitates large-scale studies of mother-infant dyads. Hospital-based studies of pregnant women and their neonates provide valuable insights within the field of perinatal health research. The aim of this study was to evaluate the effect of SARS-CoV-2 infection on maternal and perinatal outcomes among hospitalized pregnant women in Rio de Janeiro during the COVID-19 pandemic. Methods: The study consisted of a time-to-event analysis of a hospital-based cohort of 1185 pregnant women ≥ 16 years and their infants from May 2020 to March 2022. Pregnant women were classified as infected if they had a SARS CoV-2 positive RT-PCR or a positive rapid antigen test. An exploratory analysis of qualitative variables was conducted with calculation of absolute and relative frequencies and calculation of 95% confidence intervals. Survival functions were estimated by the Kaplan–Meier method, and the Cox proportional hazards model was employed to interpret the effects of SARS-CoV-2 infection on time to adverse maternal and perinatal outcomes, adjusted for vaccination, comorbidity, and gestational trimester. Results: A total of 21% (249/1185) women were infected with SARS-CoV-2, with a median age of 26 (range: 16–47). Cesarean section deliveries were performed in 57% (135/237) SARS CoV-2+ participants vs. 43% (391/914) of uninfected participants, p < 0.001. Intensive care unit admission and/or death occurred in 68 of 1185 participants (5.7%), 44 of 249 participants (17.7%) infected with SARS CoV-2 vs. 24 of 936 uninfected participants (2.5%). All 21 participants who died were unvaccinated against COVID-19. Women infected with SARS-CoV-2 were at greater risk of adverse maternal outcomes (crude HR: 5.93, 95% CI: 3.58–9.84; adjusted HR: 5.47, 95% CI: 3.16–9.48) than uninfected pregnant women. SARS CoV-2 vertical transmission was observed in 6 of 169 (3.6%) tested neonates. Preterm deliveries occurred more frequently in patients testing positive for SARS-CoV-2 (30.7% vs. 23.6). In the survival analysis, no effect of SARS-CoV-2 infection was observed on prematurity (HR: 0.92, 95% CI: 0.68–1.23) and adverse perinatal outcomes, including fetal distress (HR: 1.29, 95% CI: 0.82–2.05), stillbirth (HR: 1.07, 95% CI: 0.48–2.38), and neonatal death (HR: 0.96, 95% CI: 0.35–2.67), even after adjusting for vaccination, comorbidity, gestational trimester, and periods of time. Conclusion: The risk of maternal death due to COVID-19 highlights the need for adequate preventive measures, particularly vaccination, during the prenatal and postpartum periods.