Associations of sexual risk-taking with having intercourse before 15 years in adolescent females in Cape Breton, Nova Scotia, Canada

Background: This study was carried out to determine whether having first vaginal intercourse before 15 years of age is independently associated with sexual risk behaviours in Canadian female adolescents aged from 15 to 19 years. Methods: Self-completion surveys which included questions about sexual risk behaviours were carried out at three high schools in Cape Breton, Nova Scotia, Canada, in May 2006. The survey also contained questions asking about socioeconomic status, substance use and depression. Associations of early intercourse with risk behaviours were assessed using unadjusted and adjusted logistic regression. Results: The survey response rate was 92.5%. Of the 797 females aged 15-19 years responding, 475 had had vaginal intercourse in the previous year; 132 of these (27.8%) had intercourse before the age of 15 years. In adjusted analysis, early vaginal intercourse was associated with not using a condom at last intercourse (odds ratio (OR) 2.22; 95% confidence interval (CI) 1.40-3.54), unplanned intercourse in the previous year due to substance use (OR 2.45; 95% CI 1.49-4.04), having a casual partner at last intercourse (OR 2.10; 95% CI 1.23-3.56) and having three or more partners for vaginal intercourse in the previous year (OR 5.11; 95% CI 2.86-9.14). Conclusions: A history of having first intercourse before 15 years is associated with subsequent sexual risk-taking behaviours in adolescent females. These associations have clinical importance because the occurrence of early intercourse can alert health care providers to the possible presence of these risk behaviours. They also underscore the need to develop and assess programs which can delay the onset of sexual debut.