Chlamydia is a highly common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. This infection is often referred to as a “silent infection” because the majority of people who are infected, particularly women, experience no noticeable symptoms. Estimates suggest that up to 95% of infected women may not realize they have the bacteria. This high rate of asymptomatic infection can quietly lead to severe and long-term reproductive health complications. The following sections will explore the direct link between this prevalent infection and the ability to conceive.
How Untreated Infection Leads to Infertility
When a Chlamydia infection remains undiagnosed and untreated, the bacteria can migrate from the initial infection site in the cervix up into the upper female reproductive tract. This upward spread of the bacteria causes an inflammatory condition known as Pelvic Inflammatory Disease (PID). PID is the pathological process that directly threatens a woman’s ability to become pregnant.
The inflammation resulting from PID can affect the uterus, ovaries, and, most notably, the fallopian tubes. The body’s immune response to the persistent bacterial presence leads to the formation of scar tissue inside the delicate fallopian tubes. This scarring can cause the tubes to become partially or completely blocked, which is the primary mechanism for tubal factor infertility.
If the fallopian tubes are completely blocked, the egg and sperm cannot meet, preventing fertilization. If the tubes are only partially obstructed, the tiny hair-like structures (cilia) that normally move the fertilized egg toward the uterus become damaged. This partial blockage significantly increases the risk of an ectopic pregnancy, where the fertilized egg implants outside the uterus, usually within the scarred fallopian tube. Ectopic pregnancy is a life-threatening complication requiring immediate medical intervention and often results in the loss of the affected tube.
Factors Determining Fertility Risk
The risk of developing infertility is not the same for every person who contracts Chlamydia, as several factors influence the severity of internal damage. The duration of the infection before treatment plays a significant role. The longer the bacteria are present and untreated, the more time there is for inflammation and scarring to develop in the fallopian tubes. Some people may carry the infection for years without complications, while others develop PID quickly.
Another major determinant of reproductive damage is the occurrence of recurrent infections. Each new episode of Chlamydia can lead to cumulative damage. A person who contracts the infection multiple times faces a much higher probability of developing tubal factor infertility or ectopic pregnancy. The risk of complications such as PID and ectopic pregnancy is notably higher following repeat infections.
The individual’s unique immunological response to the bacteria also modifies the likelihood of developing complications. Some people mount an immune response that is more prone to causing excessive inflammation, which in turn leads to more pronounced scarring of the reproductive organs. This is why the presence or absence of external symptoms, such as discharge or pain, does not reliably correlate with the degree of internal, irreversible damage.
Treatment Options and Reproductive Outcomes
Fortunately, Chlamydia is highly treatable with antibiotics, which are approximately 95% effective at clearing the infection from the body. A typical treatment course rapidly eliminates the active bacterial infection. Early diagnosis and prompt treatment are paramount to preventing the initial development of PID and subsequent damage to the fallopian tubes.
However, a crucial limitation of antibiotic therapy is that it cannot reverse anatomical damage that has already occurred. Once the scarring and blockages have formed within the fallopian tubes due to a prior, untreated infection, antibiotics cannot dissolve that scar tissue. The goal of treatment in these cases shifts from preventing damage to limiting further spread and recurrence.
For individuals who have confirmed tubal damage leading to infertility, advanced reproductive technologies (ART) offer alternative paths to pregnancy. In Vitro Fertilization (IVF) bypasses the need for functional fallopian tubes entirely, as the egg is fertilized outside the body and the resulting embryo is placed directly into the uterus. Surgical options may also be explored to repair partially damaged tubes, though IVF is often the more successful route.
Risks During an Established Pregnancy
If conception occurs while a woman has an active Chlamydia infection, the risks shift away from preventing pregnancy and toward maternal and neonatal health outcomes. An active infection during gestation increases the risk of adverse events, including premature rupture of membranes and preterm delivery. Premature birth is a serious outcome that can lead to lower birth weight and other complications for the newborn.
The most significant risk is the transmission of the bacteria to the infant during a vaginal delivery. It is estimated that 30% to 50% of newborns exposed to an infected mother will contract the bacteria. This transmission can result in two main neonatal complications: Chlamydia conjunctivitis, which is a serious eye infection, and Chlamydia pneumonia, a form of lung infection.
Testing for Chlamydia is recommended early in pregnancy so that the infection can be treated with a pregnancy-safe antibiotic regimen. This treatment effectively reduces the risk of complications for both the mother and the baby, including Chlamydia conjunctivitis and pneumonia in the newborn.