premature

Occurring, growing, or existing before the customary, correct, or assigned time; uncommonly or unexpectedly early.

Born after a gestation period of less than the normal time.

Arriving too early at maturity; mature or ripe before the proper time; hence, coming into existence or occurring too soon; too early; untimely; overhasty.

Mature or ripe before the proper time.

Happening, arriving, existing, or performed before the proper or usual time; adopted too soon; too early; untimely.