This depends on whether or not the teen girl watches the show. I wouldn't particularly know a teen guy but I would say that television in general has mixed influence. Some may see it and be negatively impacted by the lifestyles shown while others may take heed of certain habits and learn from it. This is all I can think of off the top of my head.
No, it shows girl the good and bad consequences of having sex at a young age. That It can result to pregnancy. Every girl should know what it's like and teen moms show the struggles and trouble they go through everyday being a teen mom.
I'm the fence on this. On one hand it's shows the hardships a teenage mother had to face and is a good learning experience. On the other hand it shows it's okay for premarital sex, being promiscuous and such.