Get real. Babies are created the same way at all ages. The article does not say that all low birth weight babies are born to teenage mothers.
There have ALWAYS been teenage mothers and fathers and there always will be. What I don't understand is the statement that they all seem happy, is there a problem with that? Are they to wear sack cloth and ashes and cry woe is me?
We all know that these girls have a hard time and would have had an easier time of it if they started their families under different circumstances but who has a trouble free life? For every pregnant girl there is a guy involved. Some times the guy has multiple girls pregnant at the same time. Where are the articles on that?
These are human beings in a human situation and while maybe not to your liking for them it is a reality. If you can help them, help them, if they repulse you just walk around them and keep going. Don't kick people when they are down. We have done that long enough.