A 32-year-old woman presents to her general practitioner six weeks postpartum with distressing obsessive thoughts about accidentally harming her newborn. She reports spending excessive time checking on the baby and cleaning the nursery, which interferes with her ability to rest and care for herself. She denies any intent to harm her child and feels ashamed of these thoughts. Her past medical history is unremarkable, and she has no history of psychiatric disorders. On examination, she appears anxious but is cooperative and oriented. Which of the following is the most appropriate initial management strategy for her condition?