Métodos anticonceptivos

How effective is contraception?

All the methods of contraception listed below are effective. However, no method is completely (100%) reliable. The reliability for each method is given in percentages, or in numbers of women per 100 women. If the method fails in less than 1 in 100 women, the number of women who fall pregnant may be given per 1,000 women.

For example, the contraceptive injection is more than 99% effective. In other words it is effective for more than 99 women in 100. This means less than 1 woman in 100 will become pregnant each year using this method of contraception. It is hard to understand the concept of less than one woman, so in this case the number is given out of 1,000 women instead of 100. For the example of injections, between 3 and 60 women out of every 1,000 using this method will fall pregnant.

When no contraception is used, around 85 in 100 sexually active women become pregnant within one year.

The effectiveness of some methods depends on how you use them. These are called "user-dependent methods". You have to use them properly or they do not work as well. For example, the combined oral contraceptive (COC) pill (often referred to as "the pill") is more than 99% effective if taken correctly. However, if you miss pills or are sick (vomit) then it becomes less effective. Other user-dependent methods include:

• Barrier methods (male and female condoms, diaphragms and caps).

• Los progestogen-only pill (POP).

• Natural family planning.

Some methods are not so user-dependent and need to be renewed only infrequently or never. These methods tend to be more reliable and include:

• El contraceptive injection.

• Implante anticonceptivo.

• Intrauterine contraceptive devices (IUCDs) - also known as 'coils'.

• Sterilisation.

When you choose a method of contraception, you need to think about:

• How effective it is.

• Posibles riesgos y efectos secundarios.

• Plans for future pregnancies.

• Personal preference.

• Whether you have a medical condition that might affect which options are safe for you.

• Whether you take medicines that interact with the method.

Broadly, there are five main groups of contraceptive methods:

• Barrier methods of contraception which provide a physical barrier preventing the sperm and egg getting together. For example, condoms, female condoms, caps and diaphragms.

• Hormone pills, patches and rings. These are short-acting methods which use hormones taken as a pill, patch or ring.

• Long-acting reversible contraceptives. Por ejemplo, injections, implants, intrauterine contraceptive devices (IUCDs - also known as coils) u otra intrauterine systems (IUS).

• Sterilisation. This is a permanent method and either the male o female partner can be sterilised.

• Natural methods. These rely on only having sex when you are not likely to be fertile (or using barrier methods during the fertile times).

The pros and cons of each method are briefly summarised below and then linked to more information about each specific type.

The combined oral contraceptive (COC) pill is often what is meant when people say they are "on the pill" Between 3 and 90 women in 1,000 using the pill will become pregnant each year. The difference is due to how well the woman uses the pill. The pill contains two female hormones called oestrogen and progestogen. Different brands suit different people.

Advantages

• Es muy efectivo.

• Side-effects are uncommon.

• It helps to ease painful and heavy periods.

• It slightly reduces the chance of some cancers - cancers of the ovary and womb (uterus).

• The effects go away quickly when you stop it.

Disadvantages

• There is a small risk of serious problems (particularly coágulos de sangre).

• Some women have side-effects. The most common ones are bleeding between periods, mood swings and breast tenderness.

• You must remember to take it.

• It can't be used by women with certain medical conditions. Examples include uncontrolled high blood pressure, certain types of migraine and women with a past history or family history of blood clots.

• There is a very slightly higher risk of breast cancer for women who take it.

• Does not provide protection against las infecciones de transmisión sexual.

See the separate leaflet called Combined Oral Contraceptive (COC) Pill

The progestogen-only pill (POP) is sometimes called "the mini-pill". It contains just a progestogen hormone. Between 3 and 90 women in 1,000 using the POP will become pregnant.

Advantages

• Less risk of serious problems than the COC pill.

• Many women who can't take the COC pill due to a medical condition are safe to use the POP, such as smokers over the age of 35 and women with certain types of migraine.

• You can use it when you are breastfeeding.

Disadvantages

• Periods often become irregular.

• Some women have side-effects.

• You have to be more exact about the time you take it each day than you do with the COC pill. With some older POPs you have to take it within three hours of the time you took it the day before. Newer POPs have a 12-hour window before it becomes a "missed pill".

• There may be a very small extra risk of breast cancer.

See the separate leaflet called Progestogen-only Contraceptive Pill (POP).

The contraceptive patch contains the same hormones as the COC pill but in patch form. It works in the same way and has many of the same pros and cons. Between 3 and 90 women in 1,000 will become pregnant using it. The contraceptive patch is stuck on to the skin so that the two hormones are continuously delivered to the body. There is one combined contraceptive patch available in the UK, called Evra®.

Advantages

• Es muy efectivo y fácil de usar.

• You do not have to remember to take a pill every day.

• Your periods are often lighter, less painful and more regular.

• If you have sickness (vomiting) or runny stools (diarrhoea), the contraceptive patch is still effective.

Disadvantages

• Some women have skin irritation.

• Despite its discreet design, some women still feel that the contraceptive patch can be seen.

• It may come off and then not be so effective.

• It has similar risks to the pill (such as blood clots).

• Does not provide protection against sexually transmitted infections.

See the separate leaflet called Contraceptive Patch.

The contraceptive vaginal ring also contains the same hormones as the COC pill. These hormones have effects on your body which prevent you from becoming pregnant. It is a flexible, see-through ring which is just over 5 cm in diameter. It sits in your vagina for three weeks and then you have one week without it. After exactly one week, you put a new ring into your vagina. It is about as effective as the COC pill at preventing pregnancy.

Advantages

• It is effective and easy to use.

• You do not have to remember to take a pill every day.

• If you have sickness (vomiting) or runny stools (diarrhoea), the contraceptive vaginal ring is still effective.

• Your periods are very regular.

Disadvantages

• Some women (and their partners) feel it during sex.

• It may irritate your vagina and cause soreness or discharge.

• It has similar risks to the pill (such as blood clots).

• Does not provide protection against sexually transmitted infections.

See the separate leaflet called Contraceptive Vaginal Ring.

Barrier methods include male condoms, the female condom and diaphragms and caps. They prevent sperm entering the womb (uterus).

Advantages

• There are no serious medical risks or side-effects.

• Condoms help to provide protection from las infecciones de transmisión sexual.

• Male condoms are widely available.

Disadvantages

• They are not quite as reliable as other methods.

• They need to be used properly every time you have sex.

• Male condoms occasionally split or come off.

• You have to use spermicide when using a diaphragm, which may be messy or cause some irritation.

• Diaphragms and caps usually need to be fitted.

• They may interrupt sex or make it feel less spontaneous.

See the individual leaflets called Condom (Sheath), Condoms for Women, y Diaphragms and Caps para más información.

Contraceptive injections contain a progestogen hormone which slowly releases into the body. They are very effective. Between 3 and 60 women in every 1,000 using it will become pregnant. An injection is needed every 8-13 weeks, depending on which injection is used.

Advantages

• They are very effective.

• You do not have to remember to take pills.

• Once your body is used to the hormone, you often have no periods or very light periods. Particularly if you had heavy or painful periods, this is an advantage.

• You can have contraceptive injections whilst breastfeeding.

Disadvantages

• Periods may become irregular (but often lighter or stop altogether).

• After stopping, there may be a delay in your return to normal fertility for several months. It may take up to a year for your period to come back.

• Some women have side-effects. Common side-effects are gaining weight, mood changes and headaches. You cannot undo the injection, so if side-effects occur they may continue for longer than 8-13 weeks.

• The injections cause a very slight thinning of your bones.

• There may be a very small increase in the risk of breast cancer and cancer of the neck of the womb (cervix).

See the separate leaflet called Contraceptive Injection for more information.

A contraceptive implant is a small device placed under the skin. It contains a progestogen hormone which slowly releases into the body. Around 1 woman in 2,000 using the implant will become pregnant each year. It involves a small minor operation. An injection of local anaesthetic is used to numb the skin. Each implant lasts three years, after which it should be removed.

Advantages

• Es muy efectivo.

• You do not have to remember to take pills.

• They are reversible and periods return quickly once they are removed.

• Your periods tend to be very light or non-existent.

Disadvantages

• Periods may become irregular (but more often are lighter or stop altogether).

• Some women develop side-effects but these tend to settle after the first few months.

See the separate leaflet called Contraceptive Implant for more information.

An intrauterine contraceptive device (IUCD) is also known as a coil. A plastic and copper device is put into the womb (uterus). It lasts for five or more years. Between 6 and 8 women in 1,000 will become pregnant in one year of use of this method.

Advantages

• Es muy efectivo.

• You do not have to remember to take pills.

• It lasts a long time - 5-10 years.

• There are no hormones, so there are no side-effects due to hormonal changes in your body.

Disadvantages

• Your periods may become heavier or more painful.

• There is a small risk of serious problems.

• It is uncomfortable having the coil put in. (However, this is only once in 5-10 years.)

• They do not provide protection against sexually transmitted infections.

See the separate leaflet called Intrauterine Contraceptive Device for more information.

With the intrauterine system (IUS), a plastic device that contains a progestogen hormone is put into the womb (uterus). The progestogen is released at a slow but constant rate. Around 1-2 women in 1,000 will become pregnant in one year of use of this method. The IUS is also used to treat heavy periods (menorrhagia).

Advantages

• Es muy efectivo.

• You do not have to remember to take pills.

• Periods become light or stop altogether.

Disadvantages

• Side-effects may occur as with other progestogen methods such as the POP, implant and injection. However, they are much less likely, as little hormone gets into the bloodstream.

• It is uncomfortable having it put in and does not last as long as the other type of coil.

See the separate leaflet called Intrauterine System (IUS) for more information.

Most natural family planning methods involve getting to know your cycle and when you are fertile. You can then use barrier methods of contraception, or not have sex, at these times. This has very variable effectiveness, as it depends how careful you are. As many as 25 women in 100 can become pregnant using this method. However, when used very carefully, this number can be much, much lower. You have to be very committed and check your fertility regularly.

Advantages

• There are no side-effects or medical risks.

• Anybody can use this method safely as long as they are taught how to do it.

Disadvantages

• It is not as reliable as other methods.

• Fertility awareness needs proper instruction and takes 3-6 menstrual cycles to learn properly.

• If your cycles are not very regular, this can be very unreliable.

The lactational amenorrhoea method (LAM)

LAM is another type of natural family planning for women who are breastfeeding and not having periods.

Sterilisation involves an operation. It is very effective but no method of contraception is 100% reliable. Male sterilisation (vasectomy) is easier, as it can be done under local anaesthetic and is also more reliable. These methods are often used when your family is complete. You should be sure of your decision, as they are difficult to reverse.

Advantages

• Es muy efectivo.

• You do not have to think further about contraception.

Disadvantages

• It is very difficult to reverse. Indeed, when considering sterilisation, you should assume it is irreversible. You may regret your decision if you change your mind in the future.

• Female sterilisation usually needs a anestesia general. This comes with the small risks which are associated with general anaesthetics. Your tummy may feel bloated and sore for a few days after the operation.

• Men can have discomfort, bruising and swelling after the operation for a week or so.

• It takes a while before a vasectomy becomes effective. During this time you have to use another form of contraception.

Vea los folletos separados llamados Male Sterilisation (Vasectomy) y Female Sterilisation para más información.

Emergency contraception can be used if you had sex without using contraception, or if you had sex but there was a mistake with contraception. For example, a split condom or if you missed taking your usual contraceptive pills. Emergency options are a pill or an IUCD (also known as a coil). Read about anticoncepción de emergencia.

Although pregnancy is less likely around the menopause, over the age of 40 years it is still important to use contraception. There are various different types of contraception available. Many can be used until you have gone through the menopause or are aged 55 years. Read about the different types of contraception available for women who are aged 40 until their menopause.

This leaflet is just a very brief account of each method of contraception. All these methods have their own detailed leaflet for more information. Or you can contact your practice nurse, doctor, pharmacist or local family planning clinic if you want more detailed information about any of these methods.