prematurely

hair turning grey at a younger age than expected

beginning to lose hair at a younger age than expected

losing hair at a younger age than expected

developing wrinkles on the skin at a younger age than expected

seeming or feeling middle-aged when one is still young

to die before reaching the expected lifespan

to be born before the full term of pregnancy is completed

of an event or process, to stop earlier than planned

to develop signs of old age earlier than is normal

formal way to say something ends earlier than planned

of a bomb or device, to detonate before the intended time