I was just thinking about teen pregnancy. When telling teens about the consequences of sex I would think you would tell them everything, however the sad fact it can be pretty a pretty harsh reality. You don't want to depress the person, but you don't want them to run into the situation not knowing the full extent of what they're getting themselves in to. Also, some tidbits of information can cause a problem where there wasn't one, but idk.
In your opinion would it be smart or pessimistic to tell teens things like, "Don't expect him to stay if you get pregnant, even if he says he's going to," or "Some girls try to get themselves pregnant by you to trap you." I think while stuff like this could help deter a person's decision to not do it, it could also make them pessimistic about the opposite sex. (see the: "black men ain't **** / black women are all **** argument of the last how many decades)
NOTE: While I think that what God says about sex is very important and must be taught, I also thing that there should be some non-Bible based examples as well.