The article presents a rare clinical case of systemic lupus erythematosus (SLE) in a 22-year-old patient at week 33 of pregnancy, complicated by ischemic stroke, secondary antiphospholipid syndrome, thrombosis of the inferior vena cava and vessels of the lower extremities, and polysegmental pneumonia. The patient’s medical history (September 2022) showed severe muscle weakness and fever in the early postpartum period. The examination revealed increased levels of C-reactive protein (61.32 mg/L), D-dimer (8.970 mg FEU/L), interleukin-6 (19.48 pg/mL), total bilirubin (29.8 μmol/L, mostly due to the direct fraction — 11.2 μmol/L), fibrinogen (5.3 g/L), as well as a positive titer of antibodies to SARS CoV-2 (IgG=6.82). During the second pregnancy, the patient regularly experienced flu-like symptoms and headaches, for which she took paracetamol and diclofenac until week 33. Instrumental studies showed an ischemia focus in the middle cerebral artery basin on the left, multiCT pegmental right-sided pneumonia, thrombosis of the inferior vena cava and vessels of the lower extremities. Laboratory tests revealed an increase in the erythrocyte sedimentation rate (50—57 mm/h), the level of C-reactive protein (113.0—50.9 mg/L), C3-complement (2.54—2.18 g/L), D-dimer (50.4—25.8 mg U/L), interleukin-6 (14.8—37.6 pg/mL), procalcitonin (0.142 ng/mL), and immunoglobulin E (166 IU/mL). Serological tests revealed the presence of antibodies of M and G classes to SmD1 (Human Small Nuclear Ribonucleoprotein) and cardiolipins.