Can immunity during pregnancy influence SARS-CoV-2 infection? – A systematic review

Abstract

Background: During pregnancy, the maternal immune system must create and sustain tolerance to the allogeneic fetus while maintaining the ability to protect against microbial assaults. Objectives: Ascertain the immunological differences in immune cells of pregnant women that may influence SARS-CoV-2 infection. Study design: Systematic review conducted in accordance with PRISMA guidelines and registered within PROSPERO CRD42020189735. A systematic search was undertaken across ISI, PubMed, Scopus, Embase, Cochrane Library and clinical trials.gov from January 2019 up until June 2020. Eligibility criteria included COVID-19 infection, pregnancy, and availability of immune characteristics for the pregnant women. Two authors independently screened for the suitability of inclusion. Main outcome measures: Information was manually extracted from full-text articles and efforts were made to identify overlapping data. Variables extracted and analysed included the quantification of white blood cells (WBC), lymphocytes, and C-reactive protein (CRP). Results: The literature search yielded 162 studies, of which 11 were considered appropriate for selection. Only four were used in this systematic review. Our research showed that pregnant women with COVID-19 only differ from other pregnant women in their lower WBC count. The proportion of reduced lymphocyte cases is similar in both groups, as is the case of Creactive protein levels. Conclusions: In line with previous coronavirus infections, severe maternal morbidity and perinatal death with COVID-19 infection were more likely to be expected in pregnancy. Our research showed that pregnant women with COVID-19 in terms of immunity only differ from other pregnant women in their lower WBC count.