If you take it properly, over 99%. So out of 100 women taking Cerelle over the course of 1 year, less than 1 will get pregnant. This is called ‘perfect use’.
But if you forget a pill from time to time or don’t take it when you should, it’s not quite as effective. Around 91%. So for every 100 women taking it over a 12-month period, 9 will become pregnant. This is what’s known as ‘typical use’.
In short - the less mistakes you make with it, the lower your pregnancy risk.