(WHAS11) -According to a new study, twelve percent of Kentucky babies are born too early, too small, or to teenage mothers.

Kentucky ranks 39^th among 50 states in its percentage of low-weight babies, and experts attribute that to smoking.

Studies say that in some Kentucky counties, half of the women who are pregnant smoke.

The commonwealth ranks 46^th among 50 states in its percentage of babies born premature and 26^th among the 50 states for teen births.

The study was done by the Annie E. Casey Foundation.