What was the approximate percentage of Hydrogen in a supergiant star at its birth?

Answer

Typically around 70 to 75 percent

When a supergiant is born, the vast majority of its mass, generally between 70 to 75 percent, is composed of hydrogen, with helium making up most of the remainder.

What was the approximate percentage of Hydrogen in a supergiant star at its birth?
Elementhydrogencompositionstarsupergiant