975 ABO blood group, rhesus type and risk of COVID-19 in pregnant women

Abstract

Objective: There is controversy regarding the association of ABO blood group, Rhesus (Rh) type and risk of COVID-19. We tested the hypothesis that ABO blood group and Rh type are associated with COVID-19 diagnosis and symptoms during pregnancy.

Study Design: Retrospective analysis of prospectively collected data from two labor and delivery units with universal SARS-CoV-2 testing policy between March 1 and May 31, 2020. All pregnant women tested during the study period were eligible. The primary outcome was COVID-19 diagnosis. Secondary outcomes were measures of COVID-19 severity, including symptoms, ICU admission, respiratory support and treatment for COVID-19. Outcomes were compared across ABO blood groups. Women with blood group O or Rh positive blood type were compared with non-O groups and Rh negative, respectively, using univariable and multivariable analyses.

Results: Of 586 pregnant women tested, 66 (11.3%) were positive. The most common ABO blood group in the cohort was O (52.2%) and 87.4% were Rh positive. Rates of the primary outcome, COVID-19 diagnosis, were not significantly different across ABO blood groups (P=0.47). There were also no significant differences in measures of COVID-19 severity among blood groups (Table). Compared to other blood groups, the risk of COVID-19 diagnosis was not significantly different in women with group O (13.1% vs 9.3%, adjusted OR 1.43; 95% CI 0.84, 2.4). Rh positive women were at a significantly higher risk of COVID-19 diagnosis (12.3% vs 4.1%, adjusted OR 3.38; 95% CI 1.03, 11.07) and a non-significant increased risk of symptoms (6.8% vs 2.7%, adjusted OR 2.67; 95% CI 0.63, 11.32), after adjusting for ABO blood group (Figure).

Conclusion: We found no association between ABO blood group and diagnosis or severity of COVID-19 in pregnant women. However, Rhesus positive women may be at a higher risk of COVID-19.