Chlamydia is difficult to spot
Chlamydia is one of the most important preventable causes of infertility; sadly Chlamydia shows no symptoms in over 50% of people who have it and it is often difficult to tell whether you are infected. However, symptoms when they do show up can include burning or painful sensation when urinating for men and women. For women, discharge or mucus coming out of the vagina, back pain, unusual pain during sex and bleeding between periods. Similarly for men discharge or mucus from the penis, inflamed testicles, or discomfort around the tip of the penis.
It is essential if you are experiencing any of these symptoms to take a test at one of the clinics that are centred in London and other major cities because if Chlamydia is left untreated, serious problems leading to permanent damage to the sexual organs resulting in infertility in both women and in men. Experts recommend annual Chlamydia screening for all sexually active females 25 and under and for women older than 25 with risk factors such as a new sex partner or multiple partners.

Often it lies dormant for months so you could of slept with multiple people before you realise you have the STD