•The combination of C-reactive protein ≥ 21 mg/L, hemoglobin < 11.0 g/dL, and lymphopenia < 1500 mm3 on hospital admission and the presence of ground glass ≥ 50% in computer tomography increased the risk of O2 use by 4.97 and 5.33 times respectively in pregnant and postpartum women with COVID-19. Here, CRP is linked to lymphopenia.