BACKGROUNDNew-onset systemic lupus erythematosus (SLE) during pregnancy and in the postpartum period is rare, especially when complicated with pre-eclampsia, which is difficult to diagnose accurately. Here, we report a patient with new-onset SLE and antiphospholipid syndrome during pregnancy, which presented as pre-eclampsia at admission.CASE SUMMARYA 28-year-old primigravid woman was admitted to our hospital in the 27th wk of gestation with the primary diagnosis of severe pre-eclampsia. Although spasmolysis and antihypertensive therapy were administered since admission, the 24-h proteinuria of the 2nd day after admission reached 10311.0 mg. In the 47th h of admission, immunologic examinations revealed increased levels of anti-double stranded DNA antibody, anti-nuclear antibody, anti-cardiolipin antibody, anti-Sjögren’s syndrome-related antigen A antibody and anti-nucleosome antibody and decreased levels of complement C3 and C4. One hour later, ultrasonography of the lower limbs showed thrombus of the bilateral popliteal veins. The diagnosis of SLE and antiphospholipid syndrome was indicated. In the 54th h, the patient manifested with convulsion, dyspnea and blurred vision. Ten hours later, intrauterine death was revealed by ultrasonography. Emergent surgery consisting of inferior vena cava filter implantation and subsequent cesarean section was performed. Following glucocorticoid and anticoagulation therapy after delivery, the patient had an optimal response with improvements in symptoms and immunological markers.CONCLUSIONObstetricians should be aware of the symptoms and immunological examination results to distinguish pre-eclampsia and underlying SLE for optimal pregnancy outcomes.