A new study shows one in three women in Ireland who has ever been pregnant has had a crisis pregnancy.
The finding is contained in new research, published by the HSE, on crisis pregnancy, contraception and sexual health.
The report shows the average age at which Irish women first have sex has gone up slightly to 18. A previous survey found it was 17, while the male average is unchanged at 17.
Adults who received sex education at home or in school were 1.5 times more likely to use contraception the first time they had sex, when compared with those who had received sex education from other sources.
The survey also shows that 36% of pregnancies last year were unplanned, compared to 28% in a similar study in 2003.
The report from the Health Service Executive's Crisis Pregnancy Programme shows that 14% of the women opted for an abortion, with the vast majority of aborions being carried out in the UK.
Just over 3,000 people were questioned for the study, which was carried out by the Royal College of Surgeons in Ireland.
Professor Hannah McGee, Royal College of Surgeons in Ireland said: "These are very positive findings, particularly at a time when teenagers and young people are under increased pressure to become sexually active.
"The findings are backed up by the significant decrease in teenage births in Ireland over the last 10 years and in the reduction in the number of girls under age 20 travelling to the UK for abortion services."