Prevalence of Thrombocytopenia in Pregnant Women with COVID-19: A Systematic Review and Meta-Analysis

Background/Objectives: Although articles and reviews have been published on the effect of SARS-CoV-2 infection on pregnancy outcomes, they show mixed results with different hypotheses, and no work has focused specifically on the prevalence of thrombocytopenia. The objective of this systematic review and meta-analysis was to synthesize previous evidence and estimate the prevalence of thrombocytopenia in pregnant women with COVID-19. Methods: This systematic review was conducted according to the PRISMA-2020 and MOOSE guidelines. The Medline and Web of Science databases were searched in February 2024, and a meta-analysis of the overall prevalence of thrombocytopenia in pregnant women with COVID-19 was performed. The risk of bias was assessed using the Joanna Briggs Institute checklists. A leave-1-out sensitivity analysis was performed to test for disproportionate effect. Publication bias was assessed by visual inspection of funnel plots and Egger’s test. Results: A total of 23 studies met the inclusion criteria, of which 8 were included in the meta-analysis. There was significant (Q = 101.04) and substantial heterogeneity among the studies (I2 = 93.07%). There were no quality-based exclusions from the review of eligible studies. The combined effect of the studies showed a prevalence of thrombocytopenia of 22.9% (95%CI 4.8–41.0%). Subgroup analysis revealed no statistically significant difference in the pooled prevalence of thrombocytopenia ([16.5%; 30.3%]; p = 0.375. Egger’s test for bias was not significant, indicating that smaller studies did not report larger estimates of prevalence (t = 1.01, p = 0.353). Moreover, no potential publication bias was found. Our results are consistent with those obtained in pregnant women without COVID-19 infection and extend those of previous reviews of the effect of COVID-19 infection on pregnancy outcomes. Conclusions: Infection during pregnancy does not seem to be an additional risk factor for platelet count, although monitoring platelet count in pregnant women with COVID-19 may be of great importance to determine possible therapeutic strategies, especially in emergency cases.