Family planning advice may not work
In fact, they might actually have the reverse effect.
A government advisory group on teenage pregnancies recommended last year that children wanting to have sex before the age of 16 should be able to get contraception at school.
Lead researcher Dr David Paton, of Nottingham University Business School, said: "We found that as you increase access to family planning services pregnancy rates for this group either do not change or there is some evidence they go up.
"They certainly don't decrease which is what the government wants. It seems family planning seems to encourage more people to have sex, which teamed with a high contraceptive failure rate can cancel out any gain."
Dr Paton said the best way to reduce teen pregancies was to implement policies to tackle poverty and to boost educational opportunities.
He said the parents should also be more involved. In the mid-eighties a policy of informing parents if their children had been given contraception saw teen pregnancy rates hold steady after a period of sharp increases.
The policy, forced upon the government by the successful campaign of family values activist Victoria Gillick, was scrapped in 1985 following a legal challenge.
Conclusions rejected
The Family Planning Association rejected the suggestion that giving young people advice was ineffective.
Spokesperson Juliet Hillier told BBC News Online that other research had shown that access to specialist service had had a positive impact on reducing teenage pregnancy rates.
She said: "It is incredibly premature to say the government strategy is not working. Local teenage pregnancy coordinators did not draw up their three-year plans until the beginning of 2001, and we have yet to see figures for that period."
Ms Hillier admitted that family planning services could not solve the problem of teenage pregnancy in isolation.
She said schools and parents also needed to play a role in helping to boost young people's sense of self worth, and communication skills so that they felt able to refuse sex when put under pressure to have it.
Social circumstances
The researchers found that the chances of a girl getting pregnant under 16 were most likely to be influenced by her socio-economic circumstances.
For instance, underage pregnancies are more likely in those in care, and less likely in those who go on to further education.
Ministers want to halve the number of teenage pregnancies by 2010.
Latest National Statistics figures show that, even though the conception rate among under 18s fell last year, the rate among girls under 16 in England actually rose from 8.2 per 1,000 girls to 8.3 between 1999 and 2000.
The research is published in the Journal of Health Economics.