Fumbling in the dark.

How many precious minutes have you wasted pondering the perfect form of contraception? I'll let you in on a secret. There's no such thing.

If it is effective in preventing pregnancy, it may be bad for your health; if it stops you getting infections it may interrupt intercourse. Only condoms offer any protection against HIV/AIDS or other sexually transmitted diseases. And almost all contraceptives are aimed at women.

There have been huge advances over the last 20 years. However, there is still no totally effective, completely safe method of preventing pregnancy in heterosexual sex, though it is safest when women have both information and control. Many of the disadvantages here relate primarily to women in the Majority World, who often have neither. Here we profile the six most common contraceptives with a `pill' rating between one and ten - ten being excellent and one being appalling.

Sterilization

The most widespread form of birth control, this involves cutting the fallopian tubes in a woman or the vas deferens in a man. This method accounts for a third of contraceptive use worldwide and almost half in the Majority World. Despite the fact that the operation is more complex, far more women are sterilized than men. By 1992, 140 million women and 42 million men had been sterilized.

ADVANTAGES Effective and permanent, though for men it may take several months for sperm to disappear completely from semen. Few side effects if the operation is performed in appropriate conditions.

DISADVANTAGES Suitable only for those who are certain they want no children or who have completed their families. Has been a major tool in population control campaigns where people have been sterilized against their will or without their knowledge. Needs sterile conditions and trained medical staff. The most common complications of female sterilization are anesthesia-related problems, internal injury and infection. There may also be long-term side-effects such as heavier menstrual periods or lower back pain.

NI RATING:

Effectiveness

Safety

HIV/AIDS/STDs protection: none

Inter-uterine device

A small coiled, looped or T-shaped plastic or copper device inserted into the uterus with a tail reaching down to the upper vagina. IUDs prevent the egg implanting in the womb. In the 1980s they were used by 60 million women. IUDs now make up 24% of contraceptive use in the developing world but only 8% in the West.

ADVANTAGES Long-term protection which doesn't upset hormonal balance or interfere with lactation.

DISADVANTAGES Increased risk of foetus developing outside the womb (ectopic pregnancy) and pelvic inflammatory disease which can lead to infertility. Possibility of heavy bleeding, cramps and increased blood loss with a danger of anaemia. IUDs have to be inserted by medical personnel in sterile conditions. In the Majority World this is often not possible - twice the number of women die from such infections than in the West.

NI RATING:

Effectiveness

Safety

HIV/AIDS/STDs protection: none

Injectables

Contraceptives injected into women over one-to-three-month intervals. These include Depo Provera, Noristerat, Cyclofem and Mesigyna. All contain either progestin alone or both oestrogen and progestin. They have been heavily promoted in population programs and some were approved for use in the US in 1992 and in Canada in 1997.

ADVANTAGES Last for 2-3 months with no possibility of user failure and no action needed at time of intercourse.

DISADVANTAGES Side effects include: skin disorders; increased bleeding, tiredness, headaches, nausea, depression, hair loss, weight gain, loss of libido, delayed return to fertility. Risk of birth defects if used during pregnancy and possible link cancers of the breast, cervix and lining of the womb. Concerns expressed about the impact on bone density in young women. Injections need to be given in sterile conditions by trained medical personnel and with adequate follow-up. In the Majority World this is often not possible and can result in women not understanding why the drug is being given or not being warned of the possible side-effects.

NI RATING:

Effectiveness

Safety

HIV/AIDS/STDs protection: none

Barrier methods

When a rubber barrier is placed on the penis or in the vagina this prevents sperm reaching the egg. These are often used in conjunction with spermicides and include the male condom, the diaphragm, the cervical cap and the female condom. Worldwide, only 6% of heterosexual couples use condoms. They are not available or rarely used in much of Majority World though use is high in Scandinavia and Japan.

ADVANTAGES Safe and simple with no serious side effects. They reduce the risk of cervical cancer and sexually transmitted diseases and no medical supervision is required - apart from initial measurement for diaphragm and cap.

DISADVANTAGES Need to be used just before intercourse so requires co-operation between partners. High failure rate compared to other contraceptives. Occasional allergic reactions and toxic shock syndrome for women leaving diaphragms in too long and higher rates of urinary tract infection among diaphragm users.

NI RATING:

Effectiveness

Safety: Condom

HIV/AIDS/STDs protection: Condom: good

Diaphragm

Diaphragm: very little

Implants

Implants are small soft tubes containing progestin which are placed under the skin on the inside of a woman's arm. They work like a mini-Pill but prevent pregnancy for years. There are 1.5 million users of Norplant, the most common implant, most of these in the Majority World.

ADVANTAGES Implants effectively prevent pregnancy for up to 5 years.

DISADVANTAGES A trained health worker and sterile medical conditions are needed. Implants have been known to migrate and to embed themselves in the tissues of the arm, making removal difficult and painful. Side-effects can include prolonged bleeding and depression.

Dangerous if left too long because of risk of ectopic pregnancy, though women have been refused removal in the interests of population control. Like injectables, implants have been used for social control on minority women and those with mental health problems.

NI RATING:

Effectiveness

Safety

HIV/AIDS/STDs protection: none

The Pill

The `combined' birth control Pill contains low doses of the hormones oestrogen and progestin, thus preventing ovulation. The progestin-only Pill (or mini-Pill) is better for breastfeeding women but has to be taken at the same time each day.

ADVANTAGES No action need be taken at the time of intercourse. Easily accessible in most countries and under woman's control.

DISADVANTAGES Unsafe for women with high blood pressure, smokers and those over 35. Possible side effects include: nausea, headaches, depression and weight-gain. May also be linked with cervical cancer and increased risk of breast cancer.

In the Majority World the Pill is often sold over the counter with no explanation and no way of monitoring the Pill-user. If women take the Pill while breastfeeding this can reduce milk supply which may contribute to infant malnutrition, and undermine breastfeeding as a natural form of contraception. There are also risks of the hormones affecting infant development.

NI RATING:

Effectiveness

Safety

HIV/AIDS/STDs protection: none

There are many other ways of preventing conception in addition to the above. These include the rhythm method (withdrawal before ejaculation) used by many Catholics, natural family planning where sex is timed to fit in with a woman's menstrual cycle so that it avoids the fertile period; and LAM (Lactational Amenorrhea Method) spacing babies through continuous breastfeeding, which prevents women becoming pregnant. There is emergency contraception which can be taken after sex, there are other traditional herbs and methods not mentioned here and there are new types being tested but not yet on the market. Finally, there is abortion, a necessary form of birth control when contraceptives fail.