How effective is Mirena in protecting me against pregnancy?
Very effective indeed – and better than the IUD (‘coil’). Its effectiveness rate is generally reckoned to be around 99 per cent, which means that if 100 women use Mirena for a year, then only one of them would get pregnant. (Indeed, recent trials have claimed even lower failure rates than that.) It starts to protect you against pregnancy as soon as it’s been put in. Incidentally, if you decide that you now want to get pregnant, your fertility should return immediately after the device is removed.
