The survey of 16 to 24-year-olds also found 39 per cent had taken the morning-after pill and 35 per cent have failed to use contraception in the "heat of the moment".
A total of 503 women were questioned for the survey, commissioned by Marie Stopes International.
The charity said the poll showed the need to increase awareness of longer term contraceptive methods such as implants, intrauterine devices (IUD or coil) and injections.
More than three quarters of those surveyed (77 per cent) said they wanted a contraceptive they did not have to think about or plan for during sex.
Tracey McNeill, vice president of Marie Stopes International, said: "The research is very clear that most women want a contraceptive method that they can simply forget about - but many simply are unaware of the alternatives to the Pill."