Contraception is not being used by one in four young people in the UK having sex with a new partner, a survey has revealed.
The Government is now being urged by health campaigners to give sex education in schools higher priority.
The survey revealed that when a young person is preparing for a date that could lead to sex their foremost consideration is personal hygiene - not contraception.
The survey, which was conducted to mark World Contraception Day on September 26, was carried out by Marie Stopes International.
The UK results revealed 16% of young people who admitted to unprotected sex said they did not use contraception with a new partner as they forgot, 13% said their partner preferred not to use contraception and 19% said they had been drunk and forgot.
Tracey McNeill, vice-president of UK and Europe at Marie Stopes International, said: "We are calling on the Coalition Government to put sex and relationships education back on the agenda and ensure that all schools, including faith schools, teach a standardised curriculum to all 15-year-olds.
"This survey shows that more than half of the respondents had already had sex by their 18th birthday and the Government's own data shows 83% are sexually active by the same age. This highlights that schools are the best way to deliver quality information to young people before they become sexually active.
"The research is clear, where sex and relationships education is taught in conjunction with contraceptive information, more young people delay having sex and more practice safe sex."
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