I can't think of all that many. Some, such as a decreased risk of STIs, unwanted pregnancy can be avoided (almost totally) by using protection and/or the pill and choosing your partners selectively.
I just feel it's incredibly idiotic. This comes from me flicking through channels and coming to the Hills (no homo), this girl was speaking to her bf about moving in together and then she dropped this bombshell - she doesn't move in with anyone she's in a relationship with unless they're engaged. Her reason being that she's had a bunch of friends move in with their boyfriends and it goes belly up. WTF? If you're going to go belly up, getting engaged will do nothing for you, you're simply going to waste a ****load of money, bring about a ton of bad feelings and broken hearts this way.
It's the same with sex, imo it's a HUGE part of a relationship, couples should have sex (when they're ready), if you're not sexually compatible with someone, then that's a MASSIVE drawback to a relationship. If you wait so long until you're married, you've already spent a ****load on each other and this is something that could very well have the potential to mess up a relationship.
I'm not saying that people should go round on bang anyone in site obviously, but if you're both ready, willing and able then why the hell not? I only know a couple of christians personally and they both got married as soon as they left school and honestly, I think it's just because they want to get laid so bad (no offense theist brahs). My other mate works in a car hire place and it's run by christians, thus he's one of the only non christians, all those working had kids and got married at 14-16 and they honestly think he's weird because he's 19 (think he's 20 now) and he's not married and settled down. A lot of the mothers and daughters look like sisters. This brings up a whole other argument that might digress a bit - I think it's selfish and stupid to have kids that early, you're not mature enough (not by a long shot, the brain isn't even fully developed until 25) and you have no where near the financial stability you would have if you had waited until you were older (assuming you were smart with your money of course). You can't offer your children anywhere near the quality of care you can when older - this is refelected in freakonomics - the older you are when you have kids, the less likely they are to commit crimes, do drugs etc. Though of course that may bring up the causal argument that people who have kids younger are simply passing on their less than reputable genes, no offense to anyone.
Another thing that might not be too off topic is masturbating - it's not wrong at all. In fact if you've read in medical books/evolutionary books then you will know that's it's a very healthy practise. Even when you're trying to have your own kid, it INCREASES your chances of conception because it gets rid of the old backed up sperm and that's replaced with new, healthy sperm - very healthy even if you're not trying to conceive. It offers a range of other mental and physical benefits. Another thing I definitely do not agree with.