expression, adverb
for the first time in one's life
Emphasizes that the speaker has never experienced something before in their entire life. Often used with past tense or experiential expressions.
生まれて初めて海外旅行に行った。
I went on a trip abroad for the first time in my life.
こんなにおいしい料理は生まれて初めて食べた。
I've never eaten such delicious food before in my life.
初めて simply means 'for the first time' without the life-span emphasis. 生まれて初めて adds the nuance of 'in one's entire life'.
Compound of 生まれて (te-form of 生まれる 'to be born') + 初めて 'for the first time', literally 'for the first time since being born'.