Getting pregnant from anal sex is possible — 3 ways it could happen, according to women's health experts

• Getting pregnant from anal sex is extremely rare, but it is still possible in certain scenarios.
• For example, semen could leak out of the anus and onto your labia if you lie on your belly after anal.

If you think anal sex is a foolproof way to 100% avoid pregnancy, you may want to think again.

When it comes to getting pregnant from anal sex, "this occurrence is extremely rare, but not impossible," says Dr. Mary Jane Minkin, OB-GYN, and clinical professor of obstetrics and Gynecology at the Yale School of Medicine.

Anal sex in and of itself doesn't lead to conception, Minkin says. However, a couple of behaviors related to anal sex could.

Here are three scenarios where anal sex could lead to pregnancy.

1. If semen leaks out of the anus

If someone ejaculates inside of your butt, there's a chance of leakage.

Semen leaking into your vagina this way is "possible — although very unlikely," says Robin Watkins, a women's health nurse practitioner and the senior director of health care at Power to Decide.

This is most likely to happen if you lie flat on your belly, allowing it to drip directly onto your labia. For example, if you're a belly sleeper and you fall asleep after anal sex.

2. Fingering or oral post-anal

If your partner ejaculates into your anus but you continue to partake in sexual acts, it could get messy and introduce semen into your vagina.

The distance between the anus and the vagina is about 32 mm, which is a little shorter than the length of a tube of lip balm. Since these two openings are so close together, liquid from one could easily enter the other.

Activities like figering or oral sex could accidentally cause smears of sperm where they shouldnt be. It can get messy down there — especially when it's dark and you can't see what you're doing.

3. Having penis-in-vagina (PIV) sex before or after anal

Any time vaginal penetration is involved with someone who's fertile, there's a chance of conception — even if you ejaculate into the anus and not the vagina. Here's why:

• If you have PIV sex as a warm-up to anal, there is a chance of pre-cum getting you pregnant. Pre-cum is a clear fluid that the penis produces before ejaculation that can contain sperm. In fact, one small 2013 study found that about 40% of precum samples did contain some amount of active sperm.
• If you have PIV sex after your partner ejaculates into your anus, then the penis can transfer sperm from the anus into the vagina. This can also cause other health issues from spreading bacteria, like a urinary tract infection.

How to avoid pregnancy with anal sex

The chance of getting pregnant from anal sex is very slim, but it could occur in rare cases.

But since the chance is already slim, doing things like washing up after anal sex won't make a huge difference, Watkins says.

The best thing you can do is to use birth control even when you're having anal sex. Though the pill and IUDs are great for preventing pregnancy, a condom might be your best option.

With anal sex, Minkin says the risk of transmitting a sexually transmitted infection (STI) is much more likely than an unplanned pregnancy.

Since the lining of the anus is delicate, you have a higher risk of getting an STI such as HPV, gonorrhea, or HIV, Minkin says. Using a condom is the only way to lessen your risk of both STIs and pregnancy.

Best condoms

Our guide to the best condoms includes options for every shape and size to help you have safe sex.

• Best overall: Lifestyles Skyn, $11.17 on Amazon
• Best for pleasure: One Pleasure Plus, $9.48 on One
• Best for sensitive skin: Durex Avanti Bare RealFeel Non-Latex, from $14.05 on Amazon and Walgreens
• Best large: Kimono Microthin XL, $17.96 on Amazon

Insider's takeaway

Even though anal sex alone doesn't result in conception, if you have penis-in-vagina sex before or after anal sex, this can cause pregnancy.

Additionally, if semen leaks out of your butt and makes its way up your vagina, this could get you pregnant, although the chances of this are super slim.

If you don't want to get pregnant, it's best to use some kind of birth control, whether that's a barrier method or hormonal birth control, to lessen your chances.

Remember, hormonal birth control alone will not prevent STIs, so if you want to avoid these infections, œuse a condom.