A 33-year-old woman at 37 weeks' gestation presents with new-onset severe headache, visual disturbances and right upper quadrant pain. Blood pressure is 168/112 mm Hg on two measurements 15 minutes apart. Urinalysis shows 3+ protein. Platelets are 95 × 10⁹/L, AST 180 U/L and ALT 160 U/L. Which is the most appropriate next step in management?