Cushing syndrome (CS) during pregnancy is a rare condition with only a few cases reported in the literature. Misdiagnosis of CS is common because of overlapping features like fatigue, weight gain, striae and emotional changes that can occur during normal pregnancy. Changes in maternal hormones and their binding proteins complicate assessment of glucocorticoid hormone levels during gestation. CS during pregnancy is most frequently due to an adrenal adenoma and to a lesser degree to adrenocorticotropic hormone (ACTH) hypersecretion by a pituitary adenoma. Furthermore, aberrant expression of luteinizing hormone (LH) receptors in the adrenal cortex has been suggested to be involved in the pathogenesis of adrenal CS during pregnancy. We report three pregnant women with ACTH-independent Cushing's syndrome and an adrenal tumor. After uncomplicated delivery, patient 1 underwent in vivo testing for aberrant hormone receptor expression by the adenoma. Cortisol responses were found after administration of luteinizing hormone-releasing hormone (LHRH), human chorionic gonadotropin (hCG), glucagon, vasopressin and a standard mixed meal. All patients were treated with laparoscopic adrenalectomy. Adrenal tumor tissue of two patients showed positive immunohistochemical staining of LH receptors. Considering the cortisol responses to LHRH and hCG, and the development of CS during pregnancy in these patients, it is likely that ACTH-independent hypercortisolism was induced by the pregnancy-associated rise in hCG levels that activated aberrantly expressed LH receptors in the adrenal adenoma. Remarkably, adrenal adenomas may simultaneously express multiple aberrant receptors and individual ligands may play a role in the regulation of cortisol production in CS during pregnancy.