Adolescent health specialist Dr Rachel Skinner looked at the sexual experiences of 68 girls aged 14 to 19.

The study showed the girls were aware of the consequences of unprotected sex but lacked the negotiating skills to resist peer pressure.

A majority of respondents also said they regretted their first sexual experience.

Dr Skinner said a majority of the girls were not ready or prepared when they lost their virginity.

"Many of the teenagers said how sex education was something that was too little and too late in their schooling years," Dr Skinner told ABC Radio.

"These young people knew about the risks of unprotected sex ... rather than how to negotiate with a partner about having sex at the time that they feel ready for it."

The findings of the study will be presented to the Royal Australasian College of Physicians conference in Sydney on Tuesday.