Postpartum hemorrhage (PPH) is a frequent complication of pregnancy in India. Sheehan's description of postpartum hypopituitarism promoted the belief that PPH leads to necrosis of the enlarged pituitary gland of pregnancy and hypopituitarism. However, slow clinical progression suggests factors other than ischemia in its pathogenesis. Tissue necrosis could release sequestered antigens, triggering autoimmunity of the pituitary and delayed hypopituitarism in Sheehan's syndrome. Twenty-six consecutive patients with postpartum hypopituitarism were studied, 19 with Sheehan's syndrome based on a history of PPH and hormone profile suggesting pituitary failure [mean (SD) age 32.7 +/- 6.4 yr, duration of illness 5.5 +/- 3.1 yr], and seven patients with no history of PPH, categorized as "Other." Pituitary imaging and basal T(4), TSH, cortisol, LH, FSH, 17beta-estradiol, and autoantibodies against pituitary (PitAb) and thyroid (TMA) were evaluated. Controls included 28 healthy females without prior conception (22 +/- 5 yr) and 28 with prior conception (26 +/- 5 yr). Twelve of 19 (63.1%) patients with Sheehan's syndrome and one of seven in the Other group had PitAb against the 49-kDa autoantigen; neuron-specific enolase. Four of 28 (14.2%) controls without prior conception and 5 of 28 (17.8%) controls with prior conception had PitAb positivity (P < 0.001 and <0.01 vs. Sheehan's syndrome, respectively). There was no significant difference in the mean serum hormone values and TMA positivity between patients with Sheehan's syndrome and the Other group as well as patients with or without PitAb positivity. Pituitary autoimmunity may play a role in the cause of hypopituitarism following PPH.