References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Untreated STIs can cause infertility in both women and men, mainly through pelvic inflammatory disease (PID), tubal scarring and testicular complications. Chlamydia and gonorrhoea are the main culprits. The good news is that prompt testing and treatment prevent most fertility problems — these outcomes are almost entirely avoidable.
Here’s what to know.
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STIs Most Linked to Infertility
| STI | How It Can Affect Fertility |
|---|---|
| Chlamydia | PID, tubal scarring, ectopic pregnancy, epididymitis |
| Gonorrhoea | PID, tubal damage, epididymitis |
| Mycoplasma genitalium | Possible role in PID |
| Syphilis | Can cause congenital infection affecting future pregnancies |
| HIV | Doesn’t directly cause infertility but needs careful planning |
| Trichomoniasis | Linked to preterm birth and pregnancy complications |
Pelvic Inflammatory Disease (PID)
PID is the main pathway from STI to infertility. It happens when bacteria spread from the cervix or vagina into the uterus, fallopian tubes or ovaries. Inflammation can cause scarring that blocks the tubes, making pregnancy difficult or impossible and raising the risk of ectopic pregnancy.
Symptoms of PID
- Lower abdominal or pelvic pain
- Unusual discharge
- Bleeding between periods or after sex
- Fever
- Pain during sex
- Sometimes no symptoms at all
Male Fertility Impact
In men, untreated STIs can cause:
- Epididymitis — inflammation of the tube behind the testicle
- Orchitis — testicular inflammation
- Blocked vas deferens from repeated inflammation
- Rarely, significant fertility problems
Most single episodes of STI in men don’t cause lasting fertility issues, but repeated infections can.
Preventing Fertility Damage
- Regular STI testing, even without symptoms
- Prompt treatment of any infection
- Ensuring partners are treated at the same time
- Using condoms to reduce exposure
- HPV vaccination (preventing cervical cancer and its treatments)
If You’re Trying to Conceive
- Get a full STI screen before trying
- Treat any infections promptly
- See your GP if you’ve been trying for more than a year (or 6 months if over 35)
- Discuss your sexual health history with fertility clinicians if relevant
The Good News
- Most STIs don’t cause infertility
- Chlamydia and gonorrhoea are easily cured
- PID is treatable, especially when caught early
- Even after some damage, many women still conceive naturally
- Assisted reproduction offers options when damage is significant
Read more: What is chlamydia? | Untreated STIs | Untreated chlamydia
Frequently Asked Questions
Can chlamydia cause infertility even without symptoms?
Yes. Silent PID can cause damage without the person ever knowing they had an STI.
Will one episode of an STI make me infertile?
Usually not. Prompt treatment prevents most complications.
Can male fertility be affected by STIs?
Yes, though less commonly than female fertility.
Related reading
- A to Z of Sex: Sexual Health Terms Explained
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
