I think this is an appalling waste of money. I don't smoke and have never smoked, and as it happens, I deplore the fact that anybody smokes during pregnancy because of the risk to the baby. However, this measure is not going to change anyone's behaviour whatsoever. No one is any doubt that smoking during pregnancy is "bad", and being harassed by the NHS isn't going to make anyone quit.
This is a waste of money that would be better spent employing more midwives or increasing the number of scans women are given - we need a better tool for assessing the health of the unborn baby between weeks 20 and 40 than a sodding tape measure. Let's not forget that Britain has one of the highest rates of stillbirth in the developed world. I know smoking can be a factor in stillbirth, miscarriage, prematurity, low birthweight etc etc and is therefore important, but this initiative is unlikely to make women stop, because they already know they shouldn't be smoking.
The number of women who lie about smoking country-wide is probably insignificant - ok, so allegedly 1 in 4 women in the west of Scotland lie about smoking in pregnancy, but what about the rest of the country? Glasgow isn't representative of Scotland, much less the whole of the UK. It is known for having areas of economic deprivation, poor education etc etc (Glasgow is a lovely city, btw! Not meaning to knock it) which are associated with poorer health and, in fact, higher levels of smoking, alcohol abuse and drug abuse. I also think there is a culture of smoking in Glasgow, much more so than in Edinburgh or Aberdeen, across all levels of society (although that's based on personal observation, so I can't substantiate it).
I think to devote money to catching women out in a lie is shocking, particularly when there is no proof that it actually makes them stop smoking.