Objective. - In order to improve the understanding of hormonal contraceptive failures, this study evaluates the persistence of oral contraception and the use of emergency contraception (EC) during persistence incidents. We made the hypothesis of the existence of a strong link between the risk of unplanned pregnancies and these two parameters. In this study, we also evaluated women's perception of EC in order to elucidate the reasons of EC insufficient use. Methods. - One survey was carried out on Internet on a representative sample of women, aged 16-45. Results. - In this survey, 3775 French women were interviewed (source-population). We defined a target population of 2415 fertile women who had heterosexual intercourse during the last 12 months, and a population of 760 women at risk of unintended pregnancy who had unprotected sexual intercourse during the last 12 months(risk-population). A little more than 30% of the target population, meaning 20% of the source-population (n = 745) stopped their contraceptive method temporarily for an average time of two months. Almost 60% of women had a risk of unwanted pregnancy during this period without contraception, which is 59% of the risk-population. Only 20% of women among the population at risk used EC. The main reasons given for EC insufficient use were-the misperception of the risk of pregnancy, the lack of knowledge about EC and its way of use. Conclusion. - For the first time, this survey shows that 13% of women (of the source population) decide to stop temporarily their contraceptive method for an average time of two months per year. Fifty-nine percent of unplanned pregnancy situations are due to this poor contraception persistence. Although there is a need to reduce the risk of women being at risk, it seems also highly desirable to overcome the consequences of this poor persistence. Giving information about EC and a systematic prescription during contraception consultations would lead to an increased use of EC. (C) 2014 Elsevier Masson SAS. All rights reserved.