1. The risk of severe maternal morbidities associated with SARS-CoV-2 infection where higher when the Delta variant was predominant (July 2021-November 2021)

Evidence Rating Level: 2 (Good)

Over 170,000 pregnant people were infected by SARS-CoV-2 between January 2020 and February 2022, with 29,000 of them being hospitalized with COVID-19. Pregnancy is possible associated with worsened maternal outcomes with SARS-CoV-2. Several variants were identified during the pandemic, characterizing different waves. This retrospective cohort study evaluated the association between SARS-CoV-2 infection and severe maternal morbidities (SMM) in pregnant patients when different strains of SARS-CoV-2 predominated including: wild-type or Alpha (B.1.1.), Delta, or Omicron (B.1.1.529). SMM are defined as unexpected outcomes of labour and delivery that consist of 21 health indicators resulting in both short- or long-term consequences to one’s health. The study population consisted of pregnant patients in 32 hospitals spanning over 8 US states. The primary outcome was any SMM event during hospitalization for delivery, with secondary outcomes including number of SMM events, respiratory SMM, nonrespiratory SMM and nontransfusion SMM. The final study population included 3129 patients with SARS-CoV-2 and 12 504 patients without any evidence of infection. Higher rates of any SMM event were seen in those with SARS-CoV-2 than those without in all periods except for Omicron. The risk was similarly increased for wild-type strain and alpha variant periods, with the highest risk in the Delta period (70 patients [10.3%] vs 55 patients [1.5%]; OR, 7.69 [95% CI, 5.19-11.54]; P for trend < .001). This pattern was also consistent for nonrespiratory complications and nontransfusion complications. This study is unique in its analysis of adverse events specifically at time of delivery, while comparing 4 strains. Limitations include inability to account for vaccination status and not having all patients during the time of the wild-type strain undergoing testing for infection. In conclusion, the cohort study found an association of infection with SARS-CoV-2 and higher rates of SMM, with a stronger association with the Delta strain.

Click to read the study in JAMA Network Open

Image: PD

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