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How effective is contraception?

consultationAll the methods of contraception listed below are effective. However, no method is absolutely 100% reliable. The reliability for each method is given in percentages. For example, the contraceptive injection is more than 99% effective. This means that less than 1 woman in 100 will become pregnant each year using this method of contraception.

The effectiveness of some methods depend on how you use them. You have to use them properly, or they may lose their effect. For example, the 'pill' is more than 99% effective if taken correctly. If it is not (for example, if you miss a pill, etc) then it becomes less effective. Other 'user dependent' methods are barrier methods, the progestogen only pill, and natural family planning.

Some methods are not so 'user dependent' and need to be renewed only infrequently or never. These methods are: the contraceptive injection, implant, intrauterine devices, and sterilisation.

When no contraception is used, more than 80 in 100 sexually active women become pregnant within 1 year.

What are the different methods of contraception

Choosing a method of contraception involves a balance between.

  • how effective it is
  • possible risks and side-effects
  • plans for future pregnancies
  • personal preference
  • if you have a medical condition that needs to be considered.

Combined pill
Often just called 'the pill'. It is more than 99% effective if used properly. Contains oestrogen and progestogen. Works mainly by stopping ovulation. It is very popular. Different brands suit different people.

  • Some advantages - Very effective. Side-effects uncommon. Helps ease painful and heavy periods. Reduces the chance of some cancers.
  • Some disadvantages - Small risk of serious problems (eg thrombosis). Some women get side-effects. Have to remember to take it. Can't be used by women with certain medical conditions.

Progestogen only pill (POP)
Used to be called the 'mini-pill'. Contains just a progestogen hormone. More than 99% effective if used properly. Is commonly taken if the combined pill is not suitable. For example: breast-feeding women, smokers over the age of 35, and some women with migraine. Works mainly by causing a plug of mucus in the cervix that blocks sperm, and by thinning the lining of the uterus. May also stop ovulation.

  • Some advantages - Less risk of serious problems than the combined pill.
  • Some disadvantages - Periods often become irregular. Some women have side-effects. Not quite as reliable as the combined pill. May be less effective if you weigh over 70kg (11stone).

Barrier methods
These include male condoms, female condom, diaphragms, and caps. Prevents sperm entering the uterus. Male condoms are about 98% effective if used properly. Other barrier methods are slightly less effective than this.

  • Some advantages - No serious medical risks or side-effects. Helps protect from sexually transmitted infections. Condoms are widely available.
  • Some disadvantages - Not quite as reliable as other methods. Needs to be used properly every time you have sex. Male condoms occasionally split or come off.

Contraceptive injections (eg Depoprovera and Noristerat)
Contains a progestogen hormone which slowly releases into the body. More than 99% effective. Works by preventing ovulation and also has similar actions as the POP. An injection is needed every 8-12 weeks.

  • Some advantages - Very effective. Don't have to remember to take pills.
  • Some disadvantages - Periods may become irregular (but often lighter or stop altogether).

Some women have side-effects. Normal fertility after stopping may be delayed by several months. Can't undo the injection, so if side-effects occur they may persist for 8-12 weeks or slightly longer.

Contraceptive implants (eg Implanon)
An implant is a small device placed under the skin. Contains a progestogen hormone which slowly releases into the body. Is more than 99% effective. Works in a similar way to the contraceptive injection. Involves a small minor operation using local anaesthetic. Each one lasts 3 years.

  • Some advantages - Very effective. Don't have to remember to take pills.
  • Some disadvantages - Periods may become irregular (but often lighter or stop altogether). Some women develop side-effects but these tend to settle after the first few months.

Intrauterine device (IUD)
A plastic and copper device is put into the uterus. Lasts 5 or more years. It works mainly by stopping the egg and sperm from meeting. It may also prevent the fertilised egg from attaching to the lining of the uterus. The copper also has a spermicidal effect (kills sperm).

  • Some advantages - Very effective. Don't have to remember to take pills.
  • Some disadvantages - Periods may get heavier or more painful. Small risk of serious problems.

Hormone releasing intrauterine device (eg Mirena)
Otherwise called the intrauterine system (IUS). A plastic device that contains a progestogen hormone is put into the uterus. The progestogen is released at a slow but constant rate. More than 99% effective. Works in a similar way to the POP. Is also used to treat heavy periods (menorrhagia).

  • Some advantages - Very effective. Don't have to remember to take pills. Periods become light or stop altogether.
  • Some disadvantages - Side-effects may occur as with other progestogen methods such as the POP, implant and injection. However, they are much less likely as the hormone is mainly confined to the uterus (little gets into the bloodstream).

Natural methods
This involves fertility awareness. Effective if done correctly. Requires commitment and regular checking of fertility indicators such as body temperature and cervical secretions.

  • Some advantages - No side-effects or medical risks.
  • Some disadvantages - May not be as reliable as other methods. Fertility awareness needs proper instruction and takes 3-6 menstrual cycles to learn properly.

Involves an operation. Is more than 99% effective. Vasectomy (male sterilisation) stops sperm travelling from the testes. Female sterilisation prevents the egg from travelling along the Fallopian tubes to meet a sperm. Vasectomy is easier and more effective than female sterilisation. Popular when family is complete.

  • Some advantages - Very effective. Don't have to think further about contraception.
  • Some disadvantages - Very difficult to reverse. Female sterilisation usually needs a general anaesthetic.

Emergency contraception
Can be used if you had sex without using contraception. Also, 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 contraception pills - are usually effective if started within 72 hours of unprotected sex. Can be bought at pharmacies or prescribed by a doctor. It works either by preventing or postponing ovulation, or by preventing the fertilised egg from settling in the uterus (womb).
  • An IUD - inserted by a doctor or nurse can be used for emergency contraception up to 5 days after unprotected sex.

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Sexual Health

You don't need to have a lot of sexual partners to get a sexually transmitted infection (STI). Sex just once with someone who has an infection can be enough.

Common signs of an STI are:

  • unusual discharge of liquid from vagina or penis
  • pain or burning when you urinate
  • itching, rashes, lumps or blisters around the genitals
  • low abdominal pain
  • pain or bleeding during or after sex.

However, symptoms vary and many people have no symptoms at all.

Link to NHS website answering questions about sexual infections

Most STI's can be completely cured if found early enough. However, if left untreated they can be painful and uncomfortable or at worst cause permanent damage to your health and your fertility.

What is important is that you contact your general practice or a genitourinary medicine (GUM)/sexual health clinic as soon as possible. Information and tests are free and confidential. If you go to your general practice, you may have to pay a prescription charge for treatment.

Local GUM Clinic opening times, addresses, and contact number

Call 111 when you need medical help fast but it’s not a 999 emergencyNHS ChoicesThis site is brought to you by My Surgery Website