Figures from the first year of the chlamydia screening programme show one in eight girls between 16 and 19 is suffering from the infection, and that they are 43 per cent more likely to have chlamydia than women aged between 20 and 24.
Anne Weyman, chief executive of sexual health charity fpa, said sexually transmitted infections (STIs) were not given enough prominence in sex education, leaving children unaware that STIs such as chlamydia did not display symptoms and could cause infertility.
She said: "The impression from how our materials are used in schools is that the materials regarding STIs do not have as much attention as other areas."
She also said the screening programme needed to be speeded up.