Having trouble conceiving? Chlamydia can be a hidden cause. A fertility test can help detect infections early.
Everything You Need to Know About Chlamydia & Fertility
- Most chlamydia infections are asymptomatic — up to 80% of women and 50% of men have no noticeable symptoms.
- The infection spreads through sexual contact, including vaginal, oral, and anal sex, as well as through contaminated sex toys.
- Having multiple or new sexual partners significantly increases the risk of infection.
- Untreated infections can lead to PID in women, damaging the fallopian tubes and ovaries, and causing infertility or ectopic pregnancy.
- Complications in men include reduced sperm quality, blocked sperm ducts, and rarely, reactive arthritis.
What is Chlamydia?
Chlamydia is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It affects epithelial cells in the cervix, urethra, rectum, throat, and sometimes the eyes. Like gonorrhea, gonorrhoea, and syphilis, it is one of the most common STIs worldwide. Because many cases are asymptomatic, people often continue to have sexual contact with others, unknowingly transmitting the infection to their sex partners.
A chlamydial infection may appear harmless at first but can result in severe health problems if untreated, including pelvic inflammatory disease (PID), ectopic pregnancy, chronic pelvic pain, and infertility.
How Common are Chlamydia Infections?
Chlamydia is the most frequently reported bacterial STI in the United States. According to the Centers for Disease Control and Prevention (CDC), 1.64 million cases were documented in 2021, though the real number may exceed 2.8 million annually due to undetected infections. Women aged 15 to 24 account for nearly half of reported cases. Similar prevalence has been recorded in Europe by the Robert Koch Institute (RKI) in Germany and the BAG in Switzerland.
Nearly 1 in 2 Tubal Infertility Cases Tied to Past Chlamydia Infection
Several studies have quantified the strong link between chlamydial infection and infertility. Research shows that up to 45% of tubal infertility cases in women can be attributed to previous untreated chlamydia infections. Even a single episode of PID increases the risk of infertility by around 10–20%, while repeated infections may raise the risk to 40–50%.
In men, studies have shown that chlamydia is linked to reduced sperm quality: one large study reported up to a 14% reduction in normal sperm morphology in infected men, while others observed significantly higher sperm DNA fragmentation compared with fertile controls.
How Chlamydia is Transmitted
Chlamydia spreads primarily through sexual contact. Vaginal intercourse is the most common route, but anal sex and oral sex can also transmit the bacteria. Contaminated sex toys are another source if they are not cleaned properly or protected.
During childbirth, an untreated mother can transmit the bacteria to her infant, causing pneumonia or severe eye infections. The risk of infection increases significantly with multiple or new sex partners, inconsistent condom use, or lack of access to sexual health services.
Learn more about chlamydia in this podcast:
Symptoms of Chlamydia
Most infections are silent: around 80% of women and 50% of men show no signs. When symptoms occur, they are often mild and mistaken for other infectious diseases.
In women, symptoms of chlamydia include:
- unusual vaginal discharge
- irregular bleeding
- pain during sex
- burning sensation during urination caused by inflammation of the urethra
If untreated, the infection can spread to the uterus, fallopian tubes, and ovaries, leading to PID.
In men, a chlamydial infection often causes:
- urethral discharge
- pain when urinating
- swelling of the testicles due to epididymitis
Severe or chronic cases may impair sperm quality and, in rare cases, trigger reactive arthritis. Other possible symptoms include rectal pain or discharge, a sore throat, fever, or conjunctivitis in adults.
Long-Term Complications
If untreated, chlamydia can cause multiple serious complications:
- PID in women, with inflammation and scarring of fallopian tubes and ovaries, chronic pelvic pain, and infertility.
- Ectopic pregnancy, with an increased risk of life-threatening complications due to blocked fallopian tubes.
- Male infertility caused by blocked sperm ducts, reduced sperm quality, and DNA damage.
- Lymphogranuloma venereum, a rare but severe manifestation of chlamydial infection that damages lymphatic tissue.
- Neonatal problems, including pneumonia and eye infections.
These outcomes highlight why timely diagnosis and treatment are essential.
Diagnosis and Screening
Because many cases are asymptomatic, routine screening is vital. The most reliable method is a nucleic acid amplification test (NAAT). A urine sample is often used in men, while vaginal swabs or cervical swabs are common for women. Rectal and throat swabs may also be necessary depending on exposure.
Most international guidelines recommend:
- Annual chlamydia test for all sexually active women under 25.
- Screening older women and men with new or multiple sex partners.
- Testing during pregnancy to prevent neonatal health problems.
In addition, infertile couples are strongly encouraged to consider a chlamydia screening, as undiagnosed infections in either partner can contribute to blocked fallopian tubes, reduced sperm quality, and other hidden barriers to conception.
Anyone with symptoms or a partner diagnosed with an STI should see a health care provider promptly to ensure early diagnosis and appropriate treatment.
Treatment Guidelines
A chlamydia infection is curable with antibiotics. According to international treatment guidelines (CDC, WHO):
- Azithromycin, prescribed as a single dose orally.
- Doxycycline, twice daily for 7 days.
Both regimens are highly effective, but patients must avoid unprotected sex during therapy. All recent sex partners should be treated simultaneously to prevent reinfection. In some regions, expedited partner therapy allows a health care provider to prescribe medication for partners without prior examination.
A follow-up test is recommended for pregnant women or individuals with persistent symptoms. Because reinfection is common, re-testing after three months is also advised.
Prevention and Sexual Health Awareness
The most effective protection is prevention. Consistent use condoms during vaginal, oral, and anal sex significantly lowers the chance of infection. Reducing the number of sex partners, practicing mutual monogamy, and scheduling regular sexual health check-ups further reduce risk.
Addressing stigma around STIs encourages people to seek help. Honest conversations with a health care provider support timely care and reduce the burden of sexually transmitted diseases.
In this podcast you will learn what complications can arise from an untreatened chlamydia infection:
Takeaway: Protecting Fertility and Futures
Chlamydia is not only a common STI but also one of the leading preventable causes of infertility in both women and men. Because most infections remain silent, the bacteria can spread unnoticed, causing long-term damage to the fallopian tubes, ovaries, and sperm ducts. This hidden scarring explains why many cases of unexplained infertility are later linked to a past chlamydial infection.
The good news: infertility caused by chlamydia is largely preventable. With regular chlamydia tests, timely treatment following international treatment guidelines, and safer sexual practices—including consistent use condoms and open communication between sexual partners—the risk of permanent damage can be greatly reduced. By raising awareness of chlamydia, gonorrhoea, gonorrhea, and syphilis, and ensuring early access to sexual health care, societies can lower the burden of these infectious diseases and help protect the chance of building a family in the future.
