Gestational gigantomastia or gravid macromastia is a rare condition presenting as incapacitating breast enlargement during pregnancy. It is physically and psychologically debilitating for the patient. Fewer than 100 cases have been published to date. The etiology of the condition is unknown, but various theories have been proposed. Here we report a case of a 27 year old woman in her second pregnancy, with an abnormal increase in the size of breasts. Her breast size increased from 34B to 52D brassiere size. Routine antenatal, hormone, and initial autoimmune investigations were within normal limits. The patient was managed conservatively with breast support and had a spontaneous resolution in the postpartum period. During follow up she was diagnosed with systemic lupus erythematosus, making the association of the two conditions a possibility. Good knowledge about this rare condition is necessary for all doctors, especially obstetricians.