To report a rare case of late-puerperal onset of severe thrombocytopenia as low as 4000/μl in a 32-year-old woman with SLE, and to review our recent 10-year observations of 10 pregnancies in 8 patients with SLE in remission with a maintenance dose of prednisolone. A large dose of the steroid therapy abruptly improved severe thrombocytopenia and the patient was delivered a baby without complications. In our retrospective observations of pregnant SLE patients, the presence of anti-phospholipid antibodies was helpful for predicting the complications.