Even when women planning to have a child this year are excluded, there are still one in five not protecting themselves against pregnancy.
An online study of 681 women aged 18 to 45 found more than a quarter (27%) use condoms, with the same numbers using the pill. One in 20 women starts using hormonal contraception within weeks of beginning a new relationship, with 16% using it within a month.
The study for Bayer Healthcare found one in six women (17%) had used emergency contraception in the last two years and 5% had used it more than once.
However, more than a third (34%) of women who used emergency contraception said the experience did not make them consider their long-term contraception needs.
Medical director of the Dublin Well Woman Centre, Dr Shirley McQuade, was surprised such a high number of women were not using any contraception.
She pointed out that three out four women surveyed (73%) said they were not planning to have a child for at least a year.
Dr McQuade said the free cervical check had helped the Well Woman Centre to identify a number of women in sexual relationships who were not protecting themselves against pregnancy.
“There are long-acting options that a significant number of Irish women of every age could consider — like intrauterine contraception, hormonal implants and injections, all of which are reversible,” she said.
However, while more than half of the women (53%) knew that long-acting forms of contraception are suitable for women of all ages, usage is low.
The pill was considered to be the most effective form of contraception by 45% of women, followed by sterilisation (38%) and condoms (27%). And almost eight out of 10 (78%) said they discussed contraception with their partner.
Asked about family plans, one in eight (13%) intend having a child within a year, while 11% want to have a baby within two years.
For further information go to www.mycontraception.ie