One young Belfast woman interviewed for the ongoing "Towards Better Sexual Health" survey spoke of her confusion after getting pregnant at the age of 14.
"I had to get counselling. I didn't really know how and why I got pregnant," she told research officer Mr Dirk Schubotz.
As well as encouraging 1,000 young people to complete a detailed questionnaire, Mr Schubotz has carried out a series of group discussions and individual interviews with young people aged 14 to 25.
He said he frequently came across an "information deficit" that was not addressed by existing levels of sex education in the North.
"I'm not blaming teachers. I know they have a very hard job. But if parents don't deliver, the schools must step in and provide the information," he said.
Many young people said the sex education they received, or were currently receiving, at school was "factual and illustrative" but was not relevant to real life.
One young man from Belfast told Mr Schubotz: "Lessons at school teach only the mechanics of sex. They do not explain the experience."
Mr Schubotz said he had frequently come across negative attitudes towards homosexuality, particularly from young men in group discussions.
However, when he later looked at their completed questionnaires, some of them had recorded homosexual or bisexual experiences.
"Nobody in the group knows. They know they can't let on or there'll be trouble," he said. "The degree of homophobia among young men is very, very high."
Mr Schubotz said the extent of binge-drinking among the young people questioned was also disturbing.
"It's not about drinking to be in a good mood. It's about drinking to get drunk.
"Many people say they have been drunk when they first had sex," he said.
Differences in attitudes between the two main religious traditions in the North were not statistically significant, according to Mr Schubotz.
Young Protestants were slightly more likely than their Catholic counterparts to say sex before marriage was wrong.
However, there was little disapproval of sex before marriage from either. Mr Schubotz also noted there may have been a tendency among the young people to answer in the way they were expected to answer.
"Identity and religion are so intermingled in Northern Ireland," he said.
The questionnaires were distributed to schools, universities, youth clubs and other places were young people gather across Northern Ireland.
Meanwhile, the Irish Family Planning Authority will start a campaign in the autumn to provide free access to contraceptives for people under 25.
