CRP and hydrops fetalis: SD: standard deviation, CRP: C-reactive protein, IL-6: interleukin-6, LDH: lactate dehydrogenase, CXR: chest X-ray, CT: computed tomography, HRCT: high- resolution CT, HF: high flow, NIV: non-invasive ventilation, ARDS: acute respiratory distress syndrome, AKI: acute kidney injury, CNS: central nervous system, GGO: ground-glass opacity