How effective is it? Over 99% effective when used correctly. Less than 1 woman in every 100 will get pregnant each year using this method.
How does it work? The POP contains , which thickens mucus in the cervix to prevent sperm reaching an egg and thins the lining of the uterus to prevent an egg implanting, in some women it stops ovulation (eggs being released).
Advantages: Can be used by people who cannot use oestrogen, can be used by smokers over 35. You can use it if you are breastfeeding.
Disadvantages: Periods may stop, or be irregular, light, or more frequent. May be temporary side effects such as spotty skin, breast tenderness, weight change and headaches. Can rarely cause ovarian cysts.
Other facts: Must be taken at the same time every day. Not effective if taken over 3 hours late or after vomiting or severe diarrhoea. Some medicines may make it less effective.