Recurrent pelvic infections may be caused by:

• Having a sex partner who is not treated, so reinfection occurs.
• Having a new sex partner, or more than one sex partner, who spreads an infection.
• Receiving medical treatment that does not cure the infection. Typically, this happens when the wrong medication is prescribed or not all of the medication is taken.

Some women who have been infected with chlamydia develop a "hypersensitive response" when they are exposed to the bacteria again. A second infection can cause more irritation and damage to the pelvic organs that is worse than the first infection.

The risk of infertility increases with each episode of pelvic inflammatory disease (PID).

• After a single episode, the risk is about 8% (compared with 1% of women who have never had PID).¹
• With each additional episode of PID, the risk of infertility doubles or triples.²