Working with children and especially adolescents can provoke a host of new issues. One such problem is the issue of confidentiality. Let's imagine that you are working with a teenage client (I will let you pick the exact age or ponder the implications for various ages) and that client reveals certain information to you. Do you share that information with the parent? In what situations would you do so? Here is a blog post on the topic: http://www.apa.org/monitor/mar02/confidentiality.aspx It has a nice example. Let me pose a different example to you: Let's say you are working with a female teenage client and she reveals she is sexually active and believes she may be pregnant. What do you do? Use reference to back up your asnswer.

I'm a college professor, but many of my students are what is called "dual enrollment." They are high school students from ages fourteen to eighteen enrolled in college and earning college credits. They may be taking classes either at their high school, taught by college instructors, or at the college, with adult college students. For this example, I will use a sixteen-year-old who is dual enrollment and taking a class at college. I'm not qualified to answer from the perspective of a therapist, so I will be addressing this from the point of view of a teacher. Much of the law surrounding disclosure is similar for these two positions, though the circumstances may be different.
Both legally and ethically, professors cannot divulge a variety of information from or about students of any age. We cannot divulge their grades. We cannot divulge disabilities which may not be visible or known to others. We also cannot divulge personal information which they may have shared with us. For example, we cannot divulge someone's sexual orientation if they choose to remain closeted.
My students are strongly cautioned to expect and be prepared to deal with tragic or traumatic events, but they are also told to never press family members in ways that could traumatize them again. Personal stories are also to never be revealed to others without express permission.
Sometimes, personal stories come out because students must drop out of courses or college entirely or because they are explanations for why students missed exams or quit attending class. In those cases, I am bound by law and ethics to keep their reasons confidential. If the student is dropping a course or quitting school, then I have no choice but to reveal it to the dean to explain why the student should not be penalized.
In the hypothetical example that was posed, I would be bound by law and ethics not to reveal either the sexual activity or pregnancy to the parent, but only if the student was 18 or older. If the student is dual enrollment and under 18, the law would not keep me from revealing either pregnancy or sexual activity.
If the student became pregnant by an adult, especially a student or other person at the university, I would actually be bound by law to report it because a crime may have been committed. Many universities have a terrible record of concealing crimes committed on campus or reported by students. This has finally been changing in recent years, and now universities are actually required to immediately put out timely warnings to the entire student body, faculty, and staff in order to both warn the public and potentially capture the criminal.