Genital warts cannot cause infertility, but they can cause pre-cancerous changes in the cervix so you should make sure that you are up-to-date with your smears. Warts are often associated with other sexually transmitted diseases, the commonest of which is chlamydia. Chlamydia can, of course, cause infertility by blocking the fallopian tubes and most women do not know they are infected because there are commonly no other symptoms. Chlamydia can be diagnosed by taking a swab from the cervix – very much like taking a smear. Past chlamydial infection can also be diagnosed by a blood test.