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February 16, 2021

STIs, sperm health, and fertility

Let’s unpack what a sexually transmitted infection or disease might mean for your fertility; what to do if you have tested, or ever do test, positive; and how to protect your fertility.

Table of contents

  1. Can STIs cause infertility?
  2. Chlamydia
  3. Gonorrhea
  4. Herpes
  5. HIV
  6. HPV
  7. Mycoplasma/ureaplasma
  8. Secondary effects of STIs: urethritis and epididymo-orchitis
  9. How to protect your fertility

Can STIs cause infertility?

The short answer is yes, certain STIs/STDs can cause fertility issues, especially if left untreated. STIs are more likely to affect female fertility than male, because men are more likely to show symptoms and therefore receive early treatment. However, STIs can impact your reproductive system whether you show symptoms or not.

What’s the difference between an STI and an STD? An STI, sexually transmitted infection, is the presence of any of the bacteria or viruses that can cause STDs, even if they don’t develop symptoms. An STD, sexually transmitted disease, is the actual illness caused by those pathogens. We’re using STI here because these pathogens can impact fertility even if they never cause symptoms of disease.


Men typically show more severe signs of chlamydia earlier than women and seek treatment sooner, but that doesn’t let them off the hook completely. In one study, sperm DNA fragmentation in chlamydia-positive or mycoplasma-positive men was 3.2 times higher than in healthy patients. Antibiotics helped reverse the fragmentation, but catching it early gave the best results. Untreated men are also more likely to transmit the infection to a female partner, where it may not be caught as easily.

For women, chlamydia doesn’t cause fertility issues if it’s treated promptly. But the longer it goes untreated, the more likely women are to develop pelvic inflammatory disease (PID), an infection of one or more of the upper reproductive organs. Women with PID are at risk of developing scarring in their fallopian tubes, which could lead to infertility. Studies demonstrate that approximately 21% of women who have had one or more episodes of PID experience infertility.


Gonorrhea may not develop symptoms for up to 30 days, making it more likely that partners will transmit the infection to each other before seeking treatment. Untreated gonorrhea, like chlamydia, can cause PID in women, making it harder to conceive later.

For men, there isn’t as much evidence suggesting gonorrhea affects sperm quality. However, some studies show a connection between a positive diagnosis and the development of urethritis, inflammation of the urethra. Urethritis can also lead to epididymo-orchitis, inflammation of the epididymis (a duct behind the testes) and/or the testicle. These inflammatory conditions can affect male fertility—more on this in a minute.


Herpes may be one of the most common sexually transmitted infections, but surprisingly few studies have been completed to explore its connection to infertility. In one study, however—a small-scale study of 70 men—researchers found a potential connection between a herpes diagnosis and lowered sperm count. The connection was found with both herpes simplex virus (HSV)-1, which most commonly causes oral herpes, as well as HSV-2, which most commonly causes genital herpes.

Herpes is a virus, so it can’t be cleared up with antibiotics like some other STIs. However, antiviral drugs can help manage the infection, reduce breakouts, and decrease someone’s likelihood of spreading herpes. Most important is actually the herpes status of the birthing parent—while herpes is a fairly harmless infection for a healthy adult, it can be serious or even fatal for a newborn who contracts it during vaginal delivery.


The long-term effects of HIV have changed dramatically since the disease first developed. Patients have much longer life expectancies and are able to lead normal, relatively healthy lives with the help of antiretroviral therapy and preventative medications.

Severe illness (AIDS) is associated with poor semen parameters, but in minimally symptomatic or asymptomatic men with HIV, semen parameters do not seem to be impacted by the virus. However, the antiretroviral therapy used to manage HIV may have the unintended effect of impacting male fertility. Researchers have found that men with medication-managed HIV have reduced sperm motility, lower sperm counts, and lower semen volume compared to healthy men.

One of the biggest fertility concerns with an HIV diagnosis, though, is family planning safety. In a couple where only one partner is HIV-positive, attempting natural conception carries a risk of transmission to the uninfected partner (even if that risk is small, thanks to medication like PrEP).

HIV-positive men may explore fertility options that do not involve natural conception. Semen washing, for example, is a technique in which sperm is removed from the seminal fluid for use in insemination (IUI) or IVF, and may be a very effective preventative measure for HIV transmission. One study looked at over 11,000 cycles of IVF/IUI that used washed semen samples from male HIV patients, and found not a single instance of transmission to the female partner.


Human papillomavirus is the most common STI there is, and quite a bit of evidence suggests that it affects fertility parameters for both men and women. In women, HPV may be a risk factor for infertility and poor pregnancy outcomes (though it may not be an independent cause of infertility).

In a 2019 study, researchers studied semen samples from 20 male patients who were HPV positive. They found that HPV infection was detected more frequently among men with abnormal sperm parameters, suggesting that HPV may have an impact on sperm production; 75% of men who tested positive for HPV had abnormal semen analysis results, compared to 44% of men who tested negative for HPV.


Mycoplasma is a bacteria that can infect many bodily organs. Ureaplasma is one type of mycoplasma bacteria that commonly affects the genitals and urinary tract. (These are considered sexually transmitted infections, but they can spread/develop in other ways as well.)

Studies point to a link between these bacteria and male fertility issues. In one literature review, researchers found that infection with certain strains (U. urealyticum and M. hominis) was significantly more prevalent among infertile men. However, other strains did not have any correlation to infertility.

Like chlamydia, mycoplasma infection has been associated with increased DNA fragmentation in sperm. Although antibiotics do seem to reduce or reverse the effects, we still don’t fully understand the links between these bacterium and sperm quality or overall fertility.

The indirect effects of STIs on male fertility

Sometimes, it’s not the symptoms of the STI itself that causes fertility issues. Some STIs can cause secondary issues that could then affect male fertility.

Chlamydia and gonorrhea both have the potential to cause urethritis, inflammation of the urethra, the tube that carries urine from the bladder and semen from the testicles. Certain mycoplasma and ureaplasma organisms can also cause urethritis.

In women, this condition can sometimes lead to pelvic inflammatory disease, thanks to infections traveling through the lower reproductive system. In men, urethritis (or STIs) can lead to epididymo-orchitis. Orchitis is an inflammation of the testicles, often accompanied by an inflammation of the coiled tube at the back of the testicle that carries sperm (the epididymis). Bacterial epididymo-orchitis often results from untreated chlamydia or gonorrhea infection.

Evidence is limited as to the impact of this type of inflammation on male infertility, but what we know suggests an impact—and it could be long-term. In one small study, 60% of men who developed urethritis and epididymo-orchitis due to gonorrhea had abnormal semen parameters two years post-infection.

Protecting your fertility from STIs

  • Use a barrier method. Birth control pills and spermicide are great for family planning, but don’t protect against STIs. For that, you’ll need a barrier method such as a condom.
  • Get tested regularly. STI testing is part of a responsible approach to your reproductive health. The CDC recommends testing at least once a year, but potentially every three to six months if you have multiple partners.
  • Get treated immediately. If you test positive for a bacterial STI such as gonorrhea or chlamydia, the chances of long-term issues are decreased significantly if you can treat them right away. (It’s typically a simple course of antibiotics.)
  • Freeze your sperm. We don’t know what might happen in the future. Freezing a healthy sperm sample ensures that no matter what happens, you’ll have choices for your future family.
  • Test your fertility. If you have a history of sexually transmitted infection, sperm testing will help you understand any impact it may have on your fertility.

We recommend that, if you are considering sperm freezing or doing a semen analysis with the possibility of freezing sperm afterward, you complete STD testing first. Learn more.

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