Almost one in three pregnancies is unplanned, many because of "user error" among couples relying on the pill or condoms. Contraceptive failure is fuelling Britain's high abortion rate and places a heavy burden on the NHS, the National Institute for Health and Clinical Excellence(NICE) says.

In guidelines issued today, the institute says long-acting reversible contraceptives such as the coil and the contraceptive injection - which users do not have to think about every day or each time they have sex - should be offered to all women. The injection is given once every three months and the coil can remain in place for up to five years. As well as providing contraception, the methods have other advantages such as reducing or eliminating periods.

One study suggested that if 7.7 per cent of women moved from the pill to long-acting methods, unplanned pregnancies in England could be cut by 70,000 a year.

However, side-effects of such methods can include weight gain and acne. In the case of contraceptive injections, it can also take up to a year for fertility to return to normal.

Long-acting methods are unpopular in Britain, with 8 per cent of women aged 16 to 49 using them, compared to 25 per cent for the pill and 23 per cent for condoms.

Toni Belfield, of the Family Planning Association, which supports the guideline, said many GPs and sexual-health clinics offered women only the pill. She said: "There is a choice of methods but they are not being told about it. That is what women tell our helpline every day. In the high street you have a choice of fridges or washing machines, so why should contraception be dealt with differently?"

In the 1980s, long-acting methods such as the contraceptive injection were targeted at teenagers judged to be at high risk of unplanned pregnancy because of their disordered lifestyles, but Ms Belfield said that nowadays they were appropriate for all age groups: "Most abortions occur in the 20-plus age range. Unplanned pregnancy is an issue for all women, not just teenagers. Good communication between healthcare professionals and women is essential."

Chris Wilkinson, consultant in sexual and reproductive health and leader of the NICE Guideline Development Group, said long-acting methods were more cost-effective than the pill because they reduced the chances of unplanned pregnancy. About 80 women in 1,000 taking the pill get pregnant each year, mostly because of user error, compared with less than five using long-acting methods.

"The current limited use of [long-acting methods] suggests that healthcare professionals need better guidance and training so that they can help women make an informed choice. Health providers and commissioners also need a clear understanding of the relative cost-effectiveness of long-acting methods compared with other methods of contraception."

Professor Allan Templeton, president of the Royal College of Obstetricians and Gynaecologists, said women should be given the choice of any contraceptive methods after being told of their risks and benefits.

He said: "At a time when unplanned pregnancy has become a public-health issue we should be encouraging methods that are proving the most effective."

Norman Wells, director of Family and Youth Concern, said NHS money would be better spent highlighting the benefits of faithful and long-term relationships. "The indiscriminate promotion of contraception is serving to facilitate sexual experimentation among young people and further fuel the sexual health crisis," he said.