Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Although there are side effects of long term steroids such as osteoporosis,easy bruising ,decreased immunity but you need not to worry much as these are being given to your mother as replacement and in low doses.In Sheehan s syndrome as u must be knowing there is necrosis of pituitary leading to the deficiency of hormones secreted by pituitary.Therefore replacement of thyroid and corticosteroids are mandatory. But the only thing you require is the periodic assessment of level of these hormones and proper guidance of an endocrinologist. Hope that my answer is helpful to you. Let me know if I can assist you further.