Name a common sexually transmitted infection (STI) that can lead to infertility if untreated.

Chlamydia is a common sexually transmitted infection that can lead to infertility if left untreated. This bacterial infection often presents with mild or no symptoms, which can contribute to delays in diagnosis and treatment. If a woman is infected with chlamydia, the bacteria can ascend from the cervix to the uterus and into the fallopian tubes, potentially causing pelvic inflammatory disease (PID). PID can lead to scarring and damage to reproductive organs, increasing the risk of infertility and ectopic pregnancies.

While gonorrhea can also cause similar complications, chlamydia is more prevalent and is often considered the leading cause of infertility related to STIs. The other infections mentioned, such as syphilis and human papillomavirus (HPV), have their own serious health implications, but they do not commonly have the same direct association with infertility as chlamydia does. Syphilis can lead to complications in pregnancy, and HPV is primarily linked to cervical cancer and does not directly impact fertility in a way that untreated chlamydia does.