• HPV can damage eggs, the placenta, or sperm and can also complicate artificial insemination
• Chlamydia damages cells in the mucous membranes and reduces fertility
• Gonorrhea promotes cell death and pregnancy complications
• Early diagnosis improves treatment outcomes

Sexually transmitted diseases (STDs) are diseases primarily transmitted through unprotected sexual intercourse. Sexually transmitted diseases and infections are often abbreviated as STD (sexually transmitted disease) or STI (sexually transmitted infection), terms derived from English. Unfortunately, there is still a significant stigma surrounding these diseases, which is why there is still too little information being shared about them. In this article, we will therefore explain some of the effects of the most common sexually transmitted diseases on your fertility.

Human papillomavirus in women

The human papillomavirus is much better known as HPV and is also one of the most well-known sexually transmitted diseases—not least because of the availability of a vaccine.

The human papillomavirus (HPV) appears to cause damage to the egg cell or the cells of the placenta. This is particularly true when the sexual partner’s sperm is infected with HPV. The damage to the cells then causes more egg and placental cells to undergo apoptosis—that is, programmed cell death—and thus die. This makes implantation of the egg less likely or, in the worst case, even impossible. Unfortunately, this is also associated with an increased risk of HPV-related miscarriage (Ardekani, O. S., et al., 2025).

HPV also impairs the function of granulosa cells. These cells are essential for egg maturation and estrogen production. Anti-Müllerian hormone (AMH) levels can also decrease as a result of an HPV infection. Ultimately, HPV also contributes to the development of inflammatory reactions in the body, which can then have a negative impact on fertility as well (Ardekani, O. S., et al., 2025).

Anti-sperm antibodies, which trigger a defensive and destructive reaction by the female body against sperm, may also occur more frequently as a result of an HPV infection (Ardekani, O. S., et al., 2025).

Human papillomavirus in men

While an HPV infection in men can have negative effects on the female body, as described above, the male body itself is not entirely spared either. Sperm concentration decreases, and sperm morphology (shape) and motility (ability to move) also decline (Weinberg, M., et al., 2020). Sperm vitality—that is, the number of live sperm—is also impaired by infection with the human papillomavirus. Unfortunately, so-called DNA fragmentation—that is, damage to the sperm’s genetic material—is more frequently caused by the virus (Ardekani, O. S., et al., 2025). Overall, this unfortunately increases the risk of miscarriage (Weinberg, M., et al., 2020).

Effects of HPV Regardless of Gender

Due to the diverse and far-reaching effects of the human papillomavirus, an infection with this virus unfortunately tends to have just as negative an impact on artificial insemination as it does on natural conception. This may be due to an impaired egg-sperm reaction or an impaired fusion of the two cells. HPV also increases oxidative stress in the body, which can similarly have a negative impact on fertility (Ardekani, O. S., et al., 2025).

Chlamydia in Women

Chlamydia is caused by the bacterium Chlamydia trachomatis and is one of the most common sexually transmitted infections in Europe and the United States.

Unfortunately, a chlamydia infection causes direct changes in the cells of the vagina. The bacteria cause these cells to age extremely rapidly, and inflammatory reactions also frequently occur. Both of these factors contribute to an above-average rate of cell death in the vagina (Zeng, B., et al., 2026). In addition to the cells of the vagina, the cells of the uterine lining also suffer from the bacteria: one of the many possible effects is damage to their cellular barriers. This damage to the uterus can significantly hinder implantation and, unfortunately, stand in the way of a successful pregnancy (Lindsay, C. V., et al., 2023).

Interestingly, however, despite these sobering findings, not all studies suggest that overall fertility is impaired in women with a chlamydia infection. While some experts have identified a link, others have found no such association (Kristensen, T. S., et al., 2025). For example, some study authors report that a chlamydia infection increases the risk of ectopic pregnancies, recurrent implantation failure, preterm births, and other complications (Smolarczyk, K., et al., 2021). However, some other studies have been unable to demonstrate these problems and risks. As with so many things, the findings therefore remain unclear, and the results and options must likely be discussed with each patient on an individual basis. Of course, research must also continue at full speed in order to provide definitive answers (Kristensen, T. S., et al., 2025).

Chlamydia in Men

Men with a chlamydia infection typically have an unusually high number of deformed sperm and a noticeably low number of live sperm (Cui, J. J., et al., 2026). In line with this, other researchers have found that a chlamydia infection can particularly often lead to teratozoospermia. In cases of teratozoospermia or teratospermia, there are many morphologically abnormal (=deformed) sperm. Furthermore, chlamydia appears to increase the likelihood of oligozoospermia—that is, a low sperm concentration (Asaboro, N., et al., 2025).

Gonorrhea in Women

Gonorrhea is also colloquially known as the clap and is likewise caused by a bacterium. Gonorrhea appears to affect the endometrium in various ways, causing, among other things, increased inflammation and cell death (Lindsay, C. V., et al., 2023).

Presumably as a result, a gonorrhea infection also increases the risk of pregnancy complications. In particular, the risk of ectopic pregnancy, recurrent implantation failure, or preterm birth increases due to this bacterium (Smolarczyk, K., et al., 2021).

Gonorrhea in Men

A gonorrhea infection can reduce sperm count to one-third of that in men without the infection. In addition, sperm vitality (viability), motility (ability to move), and concentration decrease (Cui, J. J., et al., 2026).

Other Infections in Women

Since, unfortunately, not all infections have been sufficiently researched in people of all genders to date, we can only report on Mycoplasma genitalium when it comes to infections in women. This is also a sexually transmitted bacterium. Unfortunately, this bacterium increases the risk of ectopic pregnancies, preterm births, and miscarriages (Smolarczyk, K., et al., 2021).

Other infections in men

Infection with the bacterium Mycoplasma genitalium has been shown to reduce sperm count and concentration, thereby decreasing fertility (Cui, J. J., et al., 2026).

An imbalance in the mucous membranes caused by the bacterium Ureaplasma urealyticum also reduces sperm concentration. Similarly, sperm vitality—that is, their viability—decreases, and motility is also impaired (Cui, J. J., et al., 2026).

Although Herpes Simplex Virus 2 is related to the well-known Herpes Simplex Virus 1, which causes cold sores, it is typically transmitted sexually and occurs more frequently in the genital area. In principle, however, both virus types can appear in different locations. Here, too, the research findings are not yet conclusive: Some studies show a decrease in sperm count and morphology due to infection with Herpes Simplex Virus 2 (Salar, S. M., et al., 2025), while other studies show no negative effects on fertility (Cui, J. J., et al., 2026).

What to do if you suspect an infection?

If you or someone with whom you’ve had unprotected sex suspects that they have an infection, getting tested by a specialist is strongly recommended. Incidentally, when discussing the transmission of infections, “unprotected sexual intercourse” refers to the use of condoms or dental dams. Ultimately, sexually transmitted diseases are transmitted through the exchange of infectious bodily fluids such as vaginal secretions or semen.

If an infection is confirmed, it is therefore essential to contact and inform all individuals who may have been exposed. The earlier the infection is treated, the more successful the treatment is in most cases. These treatments have come a long way these days and can even make it possible to resume an active sex life despite an infection.

Frequently Asked Questions

Can sexually transmitted infections affect my fertility?

Yes, some sexually transmitted infections can affect fertility. For example, they can cause inflammation, damage cells in the mucous membranes, make implantation more difficult, or negatively affect the quality of sperm and eggs.

Can STIs also make artificial insemination more difficult?

Yes, some infections—especially HPV—can make not only natural conception but also artificial insemination more difficult. Reasons for this may include impaired interactions between the egg and sperm, increased oxidative stress, or damaged reproductive cells.

How can I tell if I have an STI?

Not every infection causes immediate symptoms. Some STIs go unnoticed for a long time. Possible signs include pain, discharge, a burning sensation when urinating, bleeding outside of your menstrual period, or pain during sexual intercourse—but often there are no symptoms at all. This is precisely why testing is so important if you suspect you might have an STI.

What should I do if I suspect I have an infection?

In that case, you should get tested by a specialist as soon as possible. If an infection is confirmed, it’s important to inform your sexual partners so they can also get tested and, if necessary, receive treatment.

Do condoms always provide complete protection against STIs?

Condoms and dental dams significantly reduce the risk, but they do not offer 100% protection against all infections. Nevertheless, they are among the most important measures for reducing the risk of transmission during sex.

Should I get tested for STIs if I’m trying to conceive?

This can be a good idea—especially if you have unexplained fertility issues, before undergoing fertility treatment, or if you’ve had unprotected sex with multiple partners. A test can help identify potential causes early on and allow for targeted treatment.

References

• Ardekani, O. S., Letafati, A., Dehkordi, S. E., Farahani, A. V., Bahari, M., Mahdavi, B., Ariamand, N., Taghvaei, M., Kohkalani, M., Pirkooh, A. A., Jazayeri, S. M., & Saso, L. (2025). From infection to infertility: a review of the role of human papillomavirus-induced oxidative stress on reproductive health and infertility. European journal of medical research, 30(1), 339. https://doi.org/10.1186/s40001-025-02605-4
• Weinberg, M., Sar-Shalom Nahshon, C., Feferkorn, I., & Bornstein, J. (2020). Evaluation of human papilloma virus in semen as a risk factor for low sperm quality and poor in vitro fertilization outcomes: a systematic review and meta-analysis. Fertility and sterility, 113(5), 955–969.e4. https://doi.org/10.1016/j.fertnstert.2020.01.010
• Zeng, B., Zhao, F., Zhou, F., Gu, W., Sun, F., Lv, W., Li, G., Zhang, Y., Wang, X., Lin, X., Liu, N., Wang, Y., Yang, J., Zhang, S., & Dai, Y. (2026). Sex hormone-responsive human vaginal epithelial organoids: a novel in vitro platform for studying Chlamydia trachomatis infection. Cell communication and signaling : CCS, 24(1), 121. https://doi.org/10.1186/s12964-026-02685-7
• Lindsay, C. V., Potter, J. A., Grimshaw, A. A., Abrahams, V. M., & Tong, M. (2023). Endometrial responses to bacterial and viral infection: a scoping review. Human reproduction update, 29(5), 675–693. https://doi.org/10.1093/humupd/dmad013
• Kristensen, T. S., Foldager, A., Laursen, A. S. D., & Mikkelsen, E. M. (2025). Sexually transmitted infections (Chlamydia trachomatis, genital HSV, and HPV) and female fertility: A scoping review. Sexual & reproductive healthcare : official journal of the Swedish Association of Midwives, 43, 101067. https://doi.org/10.1016/j.srhc.2025.101067
• Smolarczyk, K., Mlynarczyk-Bonikowska, B., Rudnicka, E., Szukiewicz, D., Meczekalski, B., Smolarczyk, R., & Pieta, W. (2021). The Impact of Selected Bacterial Sexually Transmitted Diseases on Pregnancy and Female Fertility. International journal of molecular sciences, 22(4), 2170. https://doi.org/10.3390/ijms22042170
• Cui, J. J., Zhong, W., Zhang, Y. Q., Zhang, X. Y., Zhang, H. Y., Li, S., & Li, C. L. (2026). Prevalence of semen abnormalities and the impact of genital pathogens on male infertility: a retrospective analysis of 131 183 patients. Asian journal of andrology, 10.4103/aja20264. Advance online publication. https://doi.org/10.4103/aja20264
• Asaboro, N., Omo-Aghoja, L., & Adeyinka, A. (2025). Association of Chlamydia Trachomatis Sero-Positivity with Male Infertility in the Niger-Delta Region of Nigeria: A Case-Control Study. Journal of the West African College of Surgeons, 16(2), 193–198. https://doi.org/10.4103/jwas.jwas_178_24
• Salar, S. M., Edalat, F., Letafati, A., Kalantar, S. M., Javanmardi, F., Najafi, A., Vakili, M., & Moattari, A. (2025). Prevalence of HSV-1/HSV-2 and CMV Infections in Infertile Men and Their Impact on Sperm Parameters: A Cross-Sectional Study in Iran. Health science reports, 8(2), e70221. https://doi.org/10.1002/hsr2.70221