Um, is it possible to get pregnant from anal sex?

Throwback to your sex-ed class: You probably (ahem, hopefully) learned that penis-in-vagina sex equals babies.

Okay, not technically. Your anus isn’t connected to your reproductive organs, so anal sex wouldn’t directly lead to a baby.

But at the same time...never say never. The vaginal and rectal openings are pretty damn close to each other, so it's definitely a possibility that some semen could slip into the vagina, says Mary Jane Minkin, M.D., clinical professor of obstetrics, gynecology and reproductive sciences at Yale School of Medicine.

“You’re not going to get a high concentration [of sperm], but you only need one sperm to get pregnant,” Minkin says. So while it’s very rare to get pregnant from anal, using it as a means of birth control is not 100 percent effective. Sorry, dudes.

Yes, one million percent. Minkin explains that while of course you want to use a condom to prevent pregnancy, you’re at even greater risk of STDs when doing it rectally, compared to vaginally.

“The lining of the anus if not designated to fight off infections,” Minkin explains. “Vaginal tissue in premenopausal women can do a much better job at fighting this off, as the vaginal lining is much tougher.”

The thing you never ever want to do is go from anal sex straight into vaginal. “Not that the vagina doesn’t have bacteria, but the rectum has even more, so you’re just adding more bacteria to the vagina,” Minkin says, which can lead to infections. If you're dead-set on doing anal sex before vaginal sex, clean things off a bit first and switch to a new condom.

And while you're at it, don't skip on the lube for anal sex: “If you don’t use it, you’ll have more tissue pulling apart, and if you have a break in skin, you’re even more vulnerable to infection,” Minkin explains.

The bottom line: There's an extremely small chance of pregnancy from unprotected anal sex, but the real risk from anal sex is getting an STI, so remember to use a condom.