I would pronounce Lauren with an 'au', just like you pron. the 'ou' in 'house'. Because to me, it just seems like a variation of the girls name Laura, pronounced like the Italian say: Lau-rah. No drawling 'aw', but a clear 'au'. In English, you say the letter 'A' like 'ey', but it's 'ah' in Italian, German, French, Dutch, Spanish and Portuguese. Majority rules! ;-)
This is just my opinion, I have never met a Lauren, but many Lauras, but they where all pronounced the European way.