Don't know! Cotton will hold up to boiling, but colors will fade and batting will shrink and/or melt. I sew at a flag company and indoor flags for schools/fire departments are treated with a spray before shipping and labeled Do Not Wash- indoor use only. There may be some health concerns about the retardants used on children's sleepwear in the US. I guess you'll have to ask the hospital. Let us know what you find out please?