And almost a fifth used no protection against pregnancy when they lost their virginity.
For more than a third of people having sex for the first time, the act was spontaneous, according to figures released to coincide with today’s launch of the second World Contraception Day.
The study found that almost one in six relied on friends for sex education with just 3% seeking advice from their doctor.
When questioned about reasons not to have sex, almost 30% of Irish men said it was out of fear that their partner could become pregnant. But just 23% of women said they were put off because they were afraid of getting pregnant.
Women are more inclined to discuss contraception, with 45% raising the topic first, compared with 22% of men. It also found that eight out of 10 women chose the form of contraception used.
The survey of 12 European countries, commissioned by Bayer Healthcare, ranked Ireland third after Malta and Iceland for the oldest age when teenagers first had sex, with the average age being 18.
Almost 20% of the Irish population first had sex between the ages of 14 and 15; 62% between 16-17 and 71% between 18-19.
Medical director of the Dublin Well Woman Centre, Dr Shirley McQuade, said the service regularly saw young men and women who had either been misinformed or uneducated on the contraception methods available to them.
“While women may be more inclined to discuss the topic with their sexual partner, it is evident that, for many, no method is used at all.”
Dr McQuade stressed that modern contraception was the most effective method of preventing unintended pregnancy.
Chief executive of the Irish Family Planning Association, Niall Behan, said World Contraception Day, also supported by Bayer Healthcare, was a helpful tool in educating young people. “The use of condoms is important in protecting against sexually transmitted infections and the guide published on World Contraception Day illustrates different forms of contraception available.”
Reality television star Kelly Osbourne is the global ambassador for the campaign and this year’s theme is Your Life, Your Body, Your Choice. The website of World Contraception Day (your-life.com) provides tips and information on the forms of contraception available.