* unprotected vaginal sex,
* unprotected anal sex,
* unprotected oral sex,
* being in genital contact with an infected partner, or
* sharing sex toys if they have not been cleaned or covered with a condom each time they are used.

If vaginal fluid or infected semen comes into contact with the eye, it can lead to conjunctivitis.

It is unclear whether a chlamydia infection can be spread by transferring vaginal fluid or infected semen on the fingers or by rubbing female genitals (vulvas) together.

As it is common for a person with the chlamydia infection to not have any symptoms, it is quite possible for them to infect a partner without knowing.

It is possible for chlamydia to be passed onto a child by her mother during childbirth. Although no obvious symptoms will be immediately apparent, the infection will often likely develop after birth, and can result in complications such as discharge in the baby’s eyes (conjunctivitis), inflammation and pneumonia.