Combined oral contraceptives are over 99% effective at preventing pregnancy when taken correctly. This means that fewer than 1 in 100 who use the combined pill as contraception will get pregnant in 1 year.
Progesterone only pills are also more than 99% effective, when taken correctly. However, in reality with ‘typical use’ (i.e., the way it’s taken by a lot of women in real life), this medication is around 91% effective in preventing pregnancy. The effectiveness of treatment may decrease if it is not taken around the same time each day. If the traditional progesterone-only pill is taken more than 3 hours late – the desogestrel (Cerazette) pill is taken more than 12 hours late – it may not be effective.
