Adrenal necrosis, a rare life threatening complication of antiphospholipid syndrome, is difficult to diagnose during pregnancy. We report the case of a 33-year-old woman with bilateral adrenal necrosis which started during the third trimester of her second pregnancy. Antiphospholipid syndrome had been diagnosed few years ago, after a thrombotic event. The pregnancy was uneventful until 36 weeks plus five days, when the patient was admitted for bilateral back ache, initially considered as uterine contractions. Labour was induced because pain persisted and was associated with major thrombocytopenia. A healthy infant was delivered vaginally on the second day, adrenal failure was diagnosed based on intense asthenia, persistent severe lumbar pain, low blood sodium and cortisol. Bilateral adrenal oedema was documented by CT scan and MRI. Symptoms resolved following administration of hydrocortisone and fludrocortisone. This case illustrates the difficulty to diagnose adrenal necrosis in the third trimester of pregnancy.