A little humble opinion of mine.

Sex before marriage is a very sensitive issue. But if handle properly it will show a great deal of enhancement and affect in a relationship. As i, myself trust that, nowadays is 21st centuries and the teenagers are all mature enough to do their decision on their own. Controlling too much will only lead to worst situation such as unwanted pregnancies. On the other way round, teaching and guiding them on safe sex not only can prevent them from falling into this problem but also will guide them through on handling relationship between a couple. Parents should know more in this and they really play a very important roles in this matter. Just as long as they know what is safe and which can be done and which is not, i believe they themselves (the teenagers), can control themselves from being hurt by anyone.

If (touch wood) anything do goes wrong still they wont do something stupid like suicide and etc. because they know, no matter what happened someone will actually support and guide them. This will help them grow up in their mindset and knowledge.