According to a study published in Archives of Sexual Behavior, people in the United States seem to be having more anal sex today than they did in the past.

In addition, the researchers learned that many women find anal sex enjoyable, while others find it painful or unpleasant and only agree to it due to some other factor. Common factors include feeling pressured by a sexual partner and wanting to avoid pregnancy, among others.

Sexual activity should be a pleasant, enjoyable, and consensual experience for both partners. If you feel pressured into something you don’t want to do, tell your partner that you don’t want to engage in that activity. Check out our guide to consent.

If you’re choosing anal sex out of a desire to avoid pregnancy, it’s important to know the facts.

Can you get pregnant from anal sex? Strictly speaking, the answer is no, and anal sex is an effective way to avoid pregnancy.

However, there are some highly unlikely scenarios that could indirectly cause pregnancy. And perhaps more importantly, there are other risks you need to be aware of.

Let’s take a closer look at the risks involved.

Semen carries millions of sperm that are hardwired to swim as vigorously as possible to find a woman’s egg. A woman is fertile when her ovary has released a ripe egg into a fallopian tube. This happens once a month.

For an egg to be fertilized, sperm must be in the vagina, so that they can swim up to and through the opening of the uterus, called the cervix. From there, sperm continue through the uterus and up into the fallopian tube where one or more sperm attempt to penetrate the egg.

But there is no internal link between the anus and the reproductive organs where a woman’s eggs are released each month, waiting for a sperm to fertilize them. Sperm has to reach the egg for pregnancy to occur.

Whenever sperm are near the vagina, however, there is some possibility that you or your partner will accidentally spread it to the vaginal canal without vaginal penetration. If all other conditions are right, some medical authorities believe that this could result in pregnancy.

Fertilization only requires one single sperm. The more recent the ejaculation, the more likely sperm outside the body is still alive and mobile.

About 1 in every 200 women surveyed told the British Medical Journal that they became pregnant without technology and without having had vaginal intercourse.

If these reports are accurate, it’s possible that the sperm was delivered to the vaginal canal some other way, such as ejaculation near the vaginal entrance, or a semen-tainted finger or sex toy being inserted.

So highly unlikely, it’s possible that stray sperm before or after unprotected anal penetration could reach the vagina. But remember that for anal sex to result in pregnancy, not only would sperm need to reach the vagina somehow, but the woman would also have to be in her fertile window. This is typically a period of three to seven days each cycle.

While sperm is most prevalent in semen (also referred to as “ejaculate” or “cum”), some research shows that it may also be present in smaller numbers in pre-ejaculate (“pre-cum”), which leaks from the penis during sex, before ejaculation. This fluid can also lead to pregnancy.

So in theory, even without ejaculation in the vagina, pregnancy could occur with vaginal penetration during foreplay leading up to anal sex. If you want to avoid pregnancy and aren’t using other methods of birth control, it’s best to avoid vaginal penetration altogether.

On the other hand, keep in mind that disease and injury are more likely from unsafe anal sex than they are from vaginal sex. It’s best to always use condoms during anal sex, though even condoms don’t offer 100 percent protection.

Anal sex is considered a high-risk activity. Remember, though, that sexually transmitted infections (STIs) can spread through vaginal sex as well.

It’s possible to have an STI without knowing it, as many have no immediate symptoms. And currently, there’s no standard test to determine whether a man has the human papilloma virus (HPV), some forms of which can lead to cancer.

The reason that anal sex increases the chances of infection is that the rectal lining is thin, dry, and delicate. It tears and bleeds easily, which provides an entry for viruses, bacteria, or parasites into the bloodstream. Even if neither partner has a serious infection, the presence of feces can lead to urinary tract infections.

Although lubricants can help prevent tearing and bleeding, recent research shows that they may also increase the risk of contracting infections.

In some cases, anal sex can lead to a weaker bowel and leakage.

Getting pregnant from anal sex is highly unlikely, but, if several different factors align, it is a remote possibility. Anal sex carries other health risks that are more likely.

If you and your partner choose to engage in anal sex, communication is key. Both of you should be tested for STIs and use a condom for protection. If you wish to prevent pregnancy and are sexually active, there are many birth control options to discuss with your doctor.

With the right precautions, it can be an enjoyable experience for both of you.