New Federal data show the nation's teen birthrate is at historic lows.
And Arizona saw the largest decline in the country from 2007 to 2010.
In those 4 years, Arizona's birthrate for girls, aged 15 to 19, fell 29 percent.
Brady Hamilton put the report together for the National Center for Health Statistics.
But he says the states decline in teen birthrates is only part of the story.
"Arizona was fairly high, it wasn't the highest, but it was fairly high, so 29% still leaves room for more decline," said Hamilton.
With 42 live births per thousand teenagers, Arizona still has one of the highest rates in the country.
Nationally the rate is about 34 births per thousand.
Mississippi has the highest rate at 55 births per thousand girls.
New Hampshire had the lowest at 16.