A 35-year-old woman is evaluated for worsening thrombocytopenia; she is pregnant at 36 weeks' gestation. Medical history is significant for immune thrombocytopenic purpura. Previous platelet counts during this pregnancy have been 80,000 to 100,000/µL (80-100 × 109/L). Her only medication is a prenatal vitamin.

On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 165/110 mm Hg, pulse rate is 95/min, and respiration rate is 18/min. Abdominal examination reveals mild right upper quadrant discomfort on palpation. Reflexes are normal, and no clonus is observed. She has lower extremity edema to the level of the knees bilaterally.

Laboratory studies:

Hemoglobin

10.5 g/dL (105 g/L)

Platelet count

21,000/µL (21 × 109/L)

Alanine aminotransferase

480 U/L

Aspartate aminotransferase

600 U/L

Creatinine

1.2 mg/dL (106.1 μmol/L)

Urinalysis

3+ protein

A peripheral blood smear is shown.

Which of the following is the most appropriate management of this patient's thrombocytopenia?