Newborn has stridor im worried took him to dr. and he said its nothing to be concerned about but i looked it up it said it is life threatening?

Different types: Stridor have different causes & presentation, it could be life- threatening in some cases due to the airways obstruction. In newborns commonly it is a benign, from the floppy airways, which improves with a prone positioning and resolves with a time. But it also could have and an opposite end of the spectrum from different causes. You always can seek a second opinion or consult ENT specialist. Best