A 68-year-old woman with long-standing hypertension and type 2 diabetes is found to have a blood pressure of 188/112 mm Hg at 36 weeks gestation. She has new-onset headache, right upper quadrant pain, and 2+ protein on urine dipstick. Platelets are 95 g/L and alanine aminotransferase is elevated. The fetus is viable with reassuring monitoring. What is the most appropriate immediate management?