Stalbridge Surgery, Station Road, Stalbridge, Dorset, DT10 2RQ

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Contraceptive Choices

How effective is contraception?

All 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. When no contraception is used, more than 80 in 100 sexually active women become pregnant within one year.
The effectiveness of some methods depends 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 taken correctly (for example, if you miss a pill or have vomiting) then it becomes less effective. Other ‘user dependent’ methods include 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 termed Long Acting Reversible Contraception (LARC). These methods include the contraceptive injection, implant, intrauterine devices (coils) and sterilisation.

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

This is often just called the ‘pill’. It is more than 99% effective if used properly. Contains oestrogen and progestogen and 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: breastfeeding 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 also 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.

Barrier methods

These include male condoms, the 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. Condoms help 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.

LARC – Long-Acting Reversible Contraception:-

Contraceptive injections (eg Depo-provera® and Noristerat®) (LARC)

Contain 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. Do not have to remember to take pills.
  • Some disadvantages – Periods may become irregular (but often lighter or stop all together). Some women have side-effects. Normal fertility after stopping may be delayed by several months. Cannot undo the injection, so if side-effects occur they may persist for longer than 8-12 weeks.

Contraceptive implants (eg Implanon®) (LARC)

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 three years.

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

Intrauterine device (IUD) (LARC)

A plastic and copper device is put into the uterus. Lasts five 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. Do not have to remember to take pills.
  • Some disadvantages – Periods may get heavier or more painful. Small risk of serious problems.

Hormone releasing intrauterine system (IUS) (LARC)

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 by making the lining of your uterus thinner so it is less likely to accept a fertilised egg. Also thickens the mucus from your cervix. Is also used to treat heavy periods (menorrhagia).

  • Some advantages – Very effective. Do not 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).

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 five days after unprotected sex.

Further information

This leaflet is just a brief account of each method of contraception. Ask your practice nurse or doctor if you want more detailed information about any of these methods, or visit

Stalbridge Surgery Contraception Appointments

Our practice nurse, Sue Kinver, is our specialist lead on sexual health matters. Please make an appointment to discuss any matters of contraception or sexual health with her.

Download a PDF Version

Contraceptive Choices (pdf)


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