premature

Concise Oxford English Dictionary © 2008 Oxford University Press:
premature/ˈpremətʃə(r)/

▶adjective

• 1 occurring or done before the proper time.

• 2 (of a baby) born before the end of the full term of gestation, especially three or more weeks before.

– derivatives
prematurely adverb,
prematurity noun.

– origin ME: from L. praematurus ‘very early’, from prae ‘before’ + maturus ‘ripe’.