The survey of 200 16-20 year-old girls also found that 55 per cent had started drinking by the time they were 14. Almost half of those questioned said spirits were their favourite tipple.
Lee Kynaston, editor of teenage magazine 19, which carried out the study, said: "While it's clear from the survey findings that sex and alcohol don't mix, the most dangerous aspect of this is the implications this has for safe sex.
"Under the influence of drink, young women are likely to forgo the use of condoms and this can lead to unwanted pregnancy, sexually transmitted diseases and the danger of being infected with the Aids virus. Our message is to think before you drink and make sure the sex you do have is the kind you don't want to forget."