Answer the following question given this paragraph: 

Symptoms of chlamydia may include a burning sensation during urination and a discharge from the vagina or penis. Chlamydia can be cured with antibiotics , but often there are no symptoms, so people do not seek treatment. Untreated chlamydia can lead to more serious problems, such as pelvic inflammatory disease (PID) . This is an infection of the uterus, fallopian tubes, and/or ovaries. It can scar a woman’s reproductive organs and make it difficult for her to become pregnant.


Q: Untreated chlamydia can lead to pelvic inflammatory disease, which affects what organ system?


A:
female reproductive system