Contraception helps people to prevent pregnancy. Methods are either hormonal or barrier. Hormonal methods change the hormone levels in a woman's body. They include the combined pill, the progesterone-only pill, a skin patch, an injection and an implant under the skin. The combined pill contains oestrogen and progesterone, which stop FSH being released, so eggs do not mature. Progesterone-only methods make the cervical mucus thicker, so sperm cannot get through to an egg.
Barrier methods physically stop sperm reaching an egg. The male condom, the female condom and the diaphragm are examples. Condoms are the only common method that also protects against sexually transmitted infections such as chlamydia and HIV.
To evaluate the methods, weigh up the advantages and disadvantages. Hormonal methods are very effective when used correctly. A pill only works if it is taken every day, so it is less effective if a user forgets pills, whereas an injection or implant lasts for weeks or years. Hormonal methods can cause side effects such as headaches, mood changes and changes in weight, and they give no protection against infections. Barrier methods have no hormonal side effects and condoms protect against infections, but they can fail if they split or are not used every time.