There is a shocking amount of unprotected sex out there, and pregnancy is the least of the worries, really.
Since early adolescence, most of us are educated about safe sex – at least in the secular school system. And if not, media messages galore inundate us on the need for protection. Yet somehow, the reality refuses to set in.
There seems to be this bizarre, global mental block, probably best compared to how people continue to smoke despite the knowledge that smoking will almost certainly kill you. Maybe there's just a large segment of society that just kind of wants to die. There's certainly no logical excuse for our bad behaviors and nasty habits.
What I have recently realized and internalized is that someone who is willing to engage in risky behavior is not contextually specific. If someone is willing to have unprotected sex with you, it's safe to assume, they have unprotected sex with others.
I don't think enough people make that mental connection. One who engages in risky sex, being unprotected sex, is engaging in risky behavior, not because they care about one person more, or trust one person less, but because for whatever reason, they just don't care enough to be cautious.
You can't expect others to do the screening for you. Relationships are full of dishonesties, not because someone might lie, but more likely they'll withhold certain truths.
It's all about your health
The fear of disease, rather than pregnancy is the more realistic fear in our day and age.
There's no excuse for having unprotected sex. You might not care about your partner's well being, but care enough about yourself.
We have no idea where others have been or what they do when they go home at night. Nice guys can have STDs, so can good girls. They might not even be aware of it – literally millions of people walk around with undiagnosed diseases. It's not based on class, race, religion or sexual orientation. And it's not only HIV/AIDS that we have to worry about. There are a whole slew of diseases out there waiting to be caught.
So do yourself and any potential partner a favor, and always insist on protection, at least until the point in the relationship where you are certain that you are exclusive, have both been tested and are comfortable enough to have a full detailed discussion about the matter. If you're not ready to talk about it, then you're certainly not ready to be doing it.