Can you provide backup for this claim? Because from what I have seen, and from the link provided below, STD, pregnancy, and abortion rates have been decreasing over the last couple of decades.
Also, countries with more thorough sex-ed programs show lower rates of teen sex than the US, which has less intensive sex-ed and more abstinence education.
http://www.guttmacher.org/pubs/fb_teens.html
I specifically point out these findings:
Countries with low levels of adolescent pregnancy, childbearing and STDs are characterized by societal acceptance of adolescent sexual relationships, combined with comprehensive and balanced information about sexuality and clear expectations about commitment and prevention of pregnancy and STDs within these relationships.
Easy access to contraceptives and other reproductive health services contributes to better contraceptive use and, in turn, low teenage pregnancy rates.
Not if nobody tells you about the fine, nor teaches you how to drive below the speed limit, but rather just says "Don't speed!"
Think of it this way. 9 out of 10 kids are going to drive. Driving has risks. Are you going to tell them not to drive until they have their own car, or are you going to teach them to drive safely? The ones that aren't going to drive until they have their own car aren't going to drive anyway. But for the ones who do drive, they should be taught how to do so safely. Even for the ones that wait for their own car, once they get it, they still need to know how to drive safely.
Practically everyone will have sex, either before or within marriage. They all need to know how to do it safely and responsibly, whenever that time comes.