Increased ideal weight during pregnancy

Recent research carried out in the United States have called into question one of the sacred rules of pregnancy: the question of weight.
According to team doctors that he has done this study, women on its way to becoming fat breasts, currently, some kilos less than they should.
In other words, these investigations advocating that weight gain is more than 12 kilos they consider normal.

But on the other hand, pregnant women often find that their gynecologist is quite intransigent with weight gain: no more than 10 kilos.
Most experts put the balance on their patients at each visit, and even rebuked if they have not followed their recommendations and have increased more than necessary.
Who is right?