Sheehan syndrome, also known as Simmond's disease, postpartum hypopituitarism or postpartum pituitary necrosis is hypopituitarism (decreased functioning of the pituitary gland), caused by necrosis due to blood loss and hypovolemic shock during and after childbirth. It is a rare complication of pregnancy, only occurring after excessive blood loss; the presence of disseminated intravascular coagulation (e.g. in amniotic fluid embolism or HELLP syndrome) also appears to be a factor in its development.