Someone asked us:

If (only) a condom is used during sex, and it is used correctly and it doesn’t rip, what are the chances pregnancy could occur? And why?

I’m gonna get all TMI on you in a sec, but if you’re worried that you or your partner might be pregnant after having sex one time while using a condom correctly, then worry no more. Chances are, nobody’s pregnant. Can I guarantee it? Nope, but when used properly (like you said you did), condoms work really, really well at preventing pregnancy.

There are a few things you should know about how a birth control method’s effectiveness is determined.

1. It looks at an entire year, not a single act of intercourse.
2. There are often two measures of effectiveness. Typical use and perfect use.

So when you hear that condoms are 98% effective, that means that if 100 couples used condoms correctly every time they had sex (i.e. perfect use) then at the end of a year 98 of them would not be pregnant and only two of them would be.

But real life is rarely perfect, especially when it comes to sex. That’s why it’s good to know that condoms are 82% effective with typical use. That means that if 100 couples used condoms for a year, but didn’t always use them correctly, then at the end of the year 82 of them would not be pregnant and 18 of them would be.

Because that’s how these things are measured, it makes it kinda hard to say what the likelihood of pregnancy is from one act of condom-protected sex. However, you can have even safer sex by using another birth control method, like the IUD or pill, with a condom.

- Nathan at Planned Parenthood