UPDATE ON BOBBI KRISTNA:Bobbi Kristina "It's Time to Let Her Go" Doctors Tell Bobby Brown!!

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There's nothing more doctors can do for Bobbi Kristina 

-- and they've told Bobby Brown it's time to withdraw 

life support ... TMZ has learned.

Family sources tell us the decision is now in Brown's 

hands -- but we're told he's refusing to make the 

painful choice today, and instead wants to wait until 

after the weekend.

The timing could not have been worse. Today is 

Bobby Brown's birthday. We're told Brown has been 

hopeful his daughter can beat the odds because 

someone in his extended family battled out of a coma 

after 8 days.

Bobbi Kristina was moved to Emory University 

Hospital Tuesday because the facility has a world 

class neurological department, but it appears doctors 

have determined there's no hope. Bobby Kristina has 

been in a medically-induced coma since Saturday, 

when was found face down in her bathtub.