Do teen pregnancy statistics mix the 18-19 yr old adults with the 16-17 year olds?

Good question. It depends which studies you are looking at. Most will define it as less than 19 years old. By changing the definition though to an earlier age the statistics will obviously change. Most news stories do not usually clarify that. For accurate numbers go to the national campaign to prevent teen pregnancy website. They are a well funded nonpartisan group with accurate information.