Drinking when pregnant advice: sensible precaution or patronising paternalism?

New government advice warns women not to drink any alcohol at all when pregnant, changing their line from previous advice which was to drink only a small amount - comments here and here in the Guardian. (The second one is by Zoe Williams and pretty nonsensical, sorry.) Is this a sensible precaution, given that doctors estimate that 7,500 foetuses are harmed every year by pregnant women drinking? Or is it patronising and paternalistic to assume that unless you scare pregnant women into complete abstention, they will choose to act irresponsibly?