How effective is contraception?
All the methods of contraception listed below are effective. However, no method is 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 do not work as well. For example, the combined oral contraceptive pill (COCP) - often referred to as 'the pill' - is more than 99% effective if taken correctly. However, if you miss a pill or have vomiting then it becomes less effective. Other user-dependent methods include barrier methods, the progestogen-only contraceptive pill (POCP) and natural family planning.
Some methods are not so user-dependent and need to be renewed only infrequently or never. These methods include the contraceptive injection, contraceptive implant, intrauterine contraceptive devices (IUCDs) - also known as 'coils' - and sterilisation.
What are the different methods of contraception?
When you choose a method of contraception you need to think about:
This is often just called the pill. Between 3 and 90 women in 1000 using the pill will become pregnant each year. The difference is due to how well the woman uses the pill. It contains oestrogen and progestogen and works mainly by stopping egg production (ovulation). It is very popular. Different brands suit different people.
This used to be called 'the mini-pill'. It contains just a progestogen hormone. It is commonly taken if the COCP is not suitable, such as in breast-feeding women, smokers over the age of 35 and some women with migraine. It works mainly by causing a plug of mucus in the neck of the womb (cervix) that blocks sperm. It also thins the lining of the womb, making it less likely the egg will implant. One type (Cerazette®) stops ovulation. This makes it extremely effective if used properly. The older type of POCP is not quite as effective. Between 3 and 90 women in 1000 using the POCP will become pregnant. If it is used well you have less chance of becoming pregnant (about 3 in 1000).
This contains the same hormones as the COCP, but in patch form. Between 3 and 90 women in 1000 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®.
This also contains the same hormones as the COCP. 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 COCP at preventing pregnancy.
These include male condoms, the female condom, diaphragms and caps. They prevent sperm entering the uterus. If used correctly, about 2 women in 100 will become pregnant. In normal (not perfect) use, 20 women in 100 will become pregnant. Other barrier methods are slightly less effective than this.
Contraceptive injections (eg, Depo-Provera® and Noristerat®)
These contain a progestogen hormone which slowly releases into the body. It is very effective. Between 2 and 60 women in every 1,000 using it will become pregnant after two years. It works by preventing ovulation and also has similar actions as the POCP. An injection is needed every 8-12 weeks.
Contraceptive implants (eg, Nexplanon®)
An 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 works in a similar way to the contraceptive injection. It involves a small minor operation using local anaesthetic. Each one lasts three years.
A plastic and copper device is put into the womb. It lasts for five or more years. Between 6-8 women in 1000 will become pregnant with one year of use of this method. 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).
A plastic device that contains a progestogen hormone is put into the uterus. The progestogen is released at a slow but constant rate. Around 2 women in 1000 will become pregnant with one year of use of this method. It works by making the lining of your womb thinner so it is less likely to accept a fertilised egg. It also thickens the mucus from the neck of your womb. Is also used to treat heavy periods (menorrhagia).
This involves fertility awareness. Around 150 women per 1000 will become pregnant using this method. It requires commitment and regular checking of fertility indicators such as body temperature and cervical secretions.
The lactation amenorrhoea method is suitable for the first six months after having a baby, if you are only breast-feeding and do not have a period. 2 women in 100 will conceive during that six months using this method.
This involves an operation. It is very effective but this can vary from surgeon to surgeon. 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, as it can be done under local anaesthetic. These methods are often used when your family is complete. You should be sure of your decision as they are difficult to reverse.
This 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.