The charity ChildLine, which answered more than 100,000 calls last year, said that more of the calls from girls aged 14 and 15 concerned pregnancy than any other issue.
Altogether 7,317 girls called the helpline about pregnancy in 1997-98, making it the fifth most common reason for a youngster to call. Almost 80 per cent of those who gave their ages to the confidential service were under 16, with a small minority aged between 10 and 12.
Britain has the highest rate of teenage pregnancy in Europe, and in the worldwide rankings comes second only to the United States.
ChildLine's report, entitled It Couldn't Happen To Me, was prepared in response to a request from the Government's Social Exclusion Unit, which is itself due to publish a report on tackling teenage pregnancy within the next few weeks.
The charity suggested that about 25 per cent of young women who were pregnant called it for advice and support.
ChildLine's chief executive, Valerie Howarth, said: "Most of our callers are between 10 and 15. We are able to reach girls who do not seem to be contacting other agencies and this could prove vital in order to ensure that they have help and support as well as information about sex, contraception and pregnancy."
ChildLine said the report painted a grim picture not only of the level of teenage pregnancy in Britain but also the gap between theoretical knowledge of contraception and the reality. The report's author, Gill Keep, said: "Children as young as 12 are having sexual relationships, often unplanned or secretly, sometimes as part of a longer term relationship.
"In the main, young people's early sexual experiences do not seem to be planned or even explicitly chosen. Peer pressure, pressure from boyfriends, too much alcohol and sheer opportunity all played a part. Young people generally know about the facts of life and contraception but they did not seem to have put their knowledge into practice."Reuse content