Recurrent pelvic infections may be caused by:
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).
Citations
Golden MR (2003). Vaginitis and sexually transmitted diseases. In DC Dale, DD Federman, eds., Scientific American Medicine, vol. 2, part 7, chap. 22. New York: WebMD.
Paavonen J, Schwartz D (2003). Pelvic inflammatory disease. In SA Morse et al., eds., Atlas of Sexually Transmitted Diseases and AIDS, 3rd ed., pp. 141–157. Edinburgh: Mosby.
WebMD Medical Reference from Healthwise