Why do they treat teenage pregnancies shocking when it's really common?

Although you make the valid point that pregnancy has unfortuneately become more common in teens, it is still a shocking thing for a parent to hear about their daughter. No parent want their kid or family to go through the embarrassment of the situation. Not that people should be outed for that, but less understanding people are likely to look at teens like that with disdain and act like they're irresponsible and unintelligent. So I do think Juno's parents reaction seems fitting.

Rynoll, it's always unusual when it happens to YOUR kid.

I think you should have done some research before posting to avoid being wrong. My five seconds of research led to the link below:

http://www.childtrends.org/?indicators=teen-pregnancy

I didn't see the treatment as shocking. In fact, it seemed to me that all the characters dealt with it in a pretty matter-of-fact manner. Yes, people react, but mostly they react by doing something. And of course time is compressed -- we see a year go by in an hour and a half -- so we see a lot of the actions and reactions and none of the normal life going on in between.

Where exactly did you think it was treated as shocking?

Edward

Premarital sex and teenage pregnancies may be common in the USA, that does not make them good or desirable. Mass murder and suicides are also common, I doubt you would work so hard to justify them. Juno's behaviour was immoral, simple as that.

Because it usually means that the mom and the kids live in poverty.

Teenage pregnancy may be common, but it's usually unplanned; that situation, as used for a cinematic premise, makes for built-in drama. "Knocked Up", for example, revolves around a grown woman dealing with an unplanned pregnancy, and found enough plot to with for an entire movie.

It's not "common". It's probably less than 10% that get pregnant before 20.