Almost 40 per cent of teens who answered a questionnaire about their sexual knowledge said the Internet is more useful than parents in providing this kind of information.
And almost one-quarter of respondents rated the Internet higher than their high-school sexual-education classes.
About 60 per cent couldn't identify Canada's age of sexual consent, which is 16, and almost 40 per cent overestimated how effective male condoms are when they're used as a sole method of birth control.
The results were unveiled Thursday at the annual meeting of the Canadian Paediatric Society in Quebec City. The project was an undertaking of Maya Kumar, a pediatric resident, and colleagues at the University of Western Ontario in London, Ont.
"The findings from my study seem to indicate that teenagers are relying on the Internet as a source of sexual information, and now we have a responsibility to make sure that the information they get is accurate and of good quality," Dr. Kumar said in an interview from London prior to the conference.
It was a small study of just 200 teens ranging in age from 14 to 17, who had all completed their secondary-school sexual-ed requirements. Questionnaires were administered over several months last summer and fall at the pediatric emergency department of a tertiary care hospital with a "fairly good catchment size" in southwestern Ontario, taking in kids from urban and rural areas, private and public schools, and religious-based and secular schools.
"I think that we have to be careful what conclusions we draw," Dr. Kumar said.
"At this point, all we can say is that a fairly good cross-section of Ontario students who've completed the minimum sexual requirements that the Ontario government feels is necessary have shown that they have some fairly serious deficiencies in knowledge."
She said almost 40 per cent did not identify that it's dangerous to smoke while you're on the birth control pill, and 27 per cent of respondents thought it was possible to get pregnant from oral sex, anal sex or mutual masturbation.
Almost 80 per cent did not identify that the morning-after pill will not terminate an existing pregnancy, Dr. Kumar said.
The students were also presented with four scenarios that represented a sexual assault, but only about 30 per cent of respondents actually identified all four cases as such.
But students demonstrated reasonably good understanding of how to prevent unwanted sexually transmitted infections, she added. The average number of questions related to the prevention of STIs that were answered correctly was 79 per cent, the study found.
As for correct answers to questions related to contraception, the average was only 43 per cent.
Dr. Kumar said every province has sex education in its high-school curricula, but she wasn't aware of studies to evaluate the impact on students' knowledge.
"It's funny because we have exams for math and we have exams for science, but we don't really have an evaluation process for our sexual education programs. I really hope that this study, as the first study, will give way to future studies across Canada that will quantify what strengths and weaknesses are present on a national scale, and that data could then be used to create a national guideline for sexual education."
The press secretary to Ontario Education Minister Leona Dombrowsky said the research is welcome.
"We agree that it is important for students to have accurate and relevant information," Mike Feenstra wrote in an e-mail.
"Health information contained in the curriculum must also be delivered in a clear and accessible way to students and that's why we offer many resources to help teachers deliver this important information."
The Canadian Press