Abstinence is not a plan for most teenagers today.
It was a poor plan when I was a teenager.
Still, it has been dropping significantly since 1991.\
"In 2014, there were 24.2 births for every 1,000 adolescent females ages 15-19, or 249,078 babies born to females in this age group.[1] Nearly eighty-nine percent of these births occurred outside of marriage.[1] The 2014 teen birth rate indicates a decline of nine percent from 2013 when the birth rate was 26.5 per 1,000.[1] The teen birth rate has declined almost continuously over the past 20 years. In 1991, the U.S. teen birth rate was 61.8 births for every 1,000 adolescent females, compared with 24.2 births for every 1,000 adolescent females in 2014. Still, the U.S. teen birth rate is higher than that of many other developed countries, including Canada and the United Kingdom.[2]"
Office of Adolescent Health, US Secretary of HHS