Giving girls under 16 contraceptives has been shown to raise the number of underage pregnancies.

This is because the policy appears to encourage teenagers to have sex.

A detailed statistical study yesterday put a huge question mark over the Government’s policy of making contraception more easily available to young girls.

Britain has the highest rate of teenage pregnancy in Europe. Figures released by the Office of National Statistics last week showed the number of under-age pregnancies rose again in 2000 after five years of gradual decline.

Dr David Paton, an economist at Nottingham University Business School, studied records of how many under-16s became pregnant and how many visited family planning clinics in 16 UK regions over a 14-year period.

In particular, Dr Paton studied the impact of the case brought by morality campaigner Victoria Gillick in the mid-1980s, in which a court ruled that doctors should tell parents if they gave contraceptives to under-age girls.

For up to a year afterwards, the number of young girls attending family planning clinics dropped dramatically. The ruling was opposed by sex education lobbyists, who said it would result in many more teenage pregnancies. It was reversed by the House of Lords in late 1985.

Dr Paton said yesterday: ‘Contrary to forecasts at the time, the Gillick ruling did not lead to an increase in under-age pregnancies.

‘My research casts doubt on current Government policy.

‘Over the past few years, we have had a massive expansion in family planning services for young people, yet there is no evidence that this has reduced either under-age pregnancy or abortion rates.’

He added: ‘Although family planning may make sexually active teenagers less likely to get pregnant, it seems that it also encourages others to start having sex.

‘Some of these will get pregnant through contraceptive failure.

‘If anything, the overall effect of expanding family planning services for under-16s has been to increase pregnancies and abortions.’

His findings - published in the Journal of Health Economics - are based on raw statistics showing pregnancy rates among girls under 16 have changed little since the mid-1970s, despite a huge expansion in contraception and advice services.

One in seven 15-year-old girls now attends a sexual health clinic - 12 times as many as in 1975, the first year they were allowed by law to dispense contraception to under-16s.

Dr Paton’s complex calculations take into account key factors such as unemployment rates and whether youngsters were in the education system and whether they lived without parents in local council care.

He examined the impact of the case brought by Mrs Gillick, which resulted in a heavy drop in the number of under-age girls in England attending family planning clinics.

He compared what happened with figures for teenage pregnancies in Scotland and England.

In England under-age pregnancies were unchanged, while those among girls aged 16 to 18 went up.

In Scotland pregnancies to girls under 16 also rose.

Dr Paton said pregnancies were higher among teenagers in care or unemployed, and lower among those in education.

He said improving education and career prospects was the best way to cut pregnancy rates because those with good opportunities are less likely to damage them by risking pregnancy.

The research was welcomed by family pressure groups.

Robert Whelan of Family and Youth Concern said: ‘It is a breakthrough to find an economist using econometric methods to demonstrate what parents have always suspected on the basis of common sense.’