No form of contraception is 100% effective
Making the contraceptive pill available without a prescription would not cut the UK's high pregnancy rate among teenagers, a leading GP has argued.
Sarah Jarvis, women's health spokeswoman for the Royal College of GPs, says women forgetting to take the pill is the problem, not availability.
Young women should be encouraged to use long-acting contraception, such as implants or the coil, Dr Jarvis says.
She debates the topic at the British Medical Journal Online.
Writing for the same website, Dr Daniel Grossman, of the University of California, San Francisco, says US data suggests that for some women the prescription requirement represents a barrier to women deciding and continuing to use the pill.
He called the prescription requirement "an out-of-date, paternalistic barrier to contraceptive use that is not evidence based".
He writes: "If governments are committed to addressing the challenge of unintended pregnancy - and the related problem of maternal mortality in the developing world, health systems must create mechanisms to allow freer access to hormonal contraception for all women at low or no cost."
As part of its £26.8m bid to cut unintended pregnancy rates, the UK government recently gave the go-ahead to pilots within London allowing women and girls aged over 16 to get the pill at chemists without a prescription.
If the pilots are successful, the pill could become available over-the-counter like the morning-after pill.
But Dr Jarvis said although the schemes might be safe, they would not work.
Studies suggest that nearly half of all women taking the oral contraceptive pill miss one or more pills in each cycle, and nearly a quarter miss two or more.
These women are three times more likely to get pregnant unintentionally than those who take the pill consistently.
Dr Jarvis said: "Increased uptake of reliable, non user-dependent methods has to be the key.
"Rather than making a potentially unreliable method of contraception more easily available, our best avenue for reducing unplanned pregnancies is to encourage general practitioners to help their patients to make the best choices."
A spokesman for the Department of Health said: "We want to improve women's access to contraception and help reduce the number of unintended pregnancies and have invested £26.8 million in 2008/09 to do this.
"This will include a new targeted campaign to highlight the full range of contraceptive choices available to women, including the more effective long-acting reversible contraception."
Simon Blake, chief executive of Brook, said: "Increased access to free contraception for all women is vital to reducing unwanted pregnancy rates.
"Long-acting methods of contraception are very effective and access still needs to be improved.
"People must be helped to make informed choices about the type of contraception that is right for them and suits their lifestyle."
A spokeswoman for the Family Planning Association said: "Contraceptive choice and access are both extremely important and making the pill available in pharmacies means that the millions of women already using it will find it easier to obtain."
Although the teenage pregnancy rate in Britain is falling in many areas, it remains the highest in Western Europe.