Teenage smoking and birth.

Reading the news today I came across this article about teenagers smoking. I was shocked to say the least, and I am not really sure that I agree entirely with the article headline, as I cannot see the majority starting to smoke to reduce size of the baby. I am sure most of it comes from peer pressure, copying parents or just being a rebel and of course already being a smoker.
One good thing that I can see to reduce smokers is making it harder for smoker to find places to smoke and socialise , which is already happening throughout the country.