Thrombocytopaenia and COVID-19 infection during pregnancy increases the risk of preeclampsia: a multicentre study

Research question: Is a low platelet count related to an increased risk of severe disease in pregnant women with active severe acute respiratory syndrome coronavirus 2 infection? Design: A cross-sectional multicentre study in pregnant women with COVID-19 confirmed by polymerase chain reaction, antigen test, antibody test, or all. Results: A total of 153 pregnant women with COVID-19 were included in the study, of whom 12.4% had thrombocytopaenia. Pregnant women with thrombocytopaenia were on average 3.1 years older (95% CI 0.18 to 6.38) than women without thrombocytopaenia. Pregnant smokers had a higher risk of thrombocytopaenia than non-smokers (OR 6.55, CI 95% 1.29 to 33.13). B Rh negative (B Rh–) pregnant women had a much higher risk of thrombocytopaenia than pregnant women with other blood groups (OR 16.83, CI 95% 1.42 to 199.8). Pregnant women with thrombocytopaenia had a much higher risk of suffering from preeclampsia (OR 16.2, CI 95% 1.35 to 193.4). Conclusions: COVID-19 infection is not a risk factor for a low platelet count in pregnant women, although the risk is increased by smoking and in women with blood group B Rh–. In case of pregnancy with thrombocytopaenia, COVID-19 infection leads to an increased risk of preeclampsia.