The morning after pill helps reduce the risk of unplanned pregnancy following contraceptive failure or unprotected sex by delaying ovulation, so the egg is not released and any sperms that are in your vagina won’t have anything to fertilise.
Regardless of your body weight or BMI, you should take emergency contraception as soon as possible after unprotected sex in order to reduce the risk of unplanned pregnancy. Your emergency contraceptive options are the hormonal emergency contraceptive pill (ulipristal acetate, the active ingredient in ellaOne®, or levonorgestrel) or the intrauterine device (IUD).
But is emergency contraception less effective if you weigh more?
“There appears to be limited and inconclusive data which suggests that levonorgestrel is less effective in women with a BMI over 26 and/or who weigh over 70 kilogrammes,” says Deborah. “Ulipristal acetate may be less effective in women with a BMI over 30 or weight greater than 85 kilogrammes.”
What little data we have is limited and inconclusive, so it’s really hard to determine causation or say for sure whether a morning after pill would be less effective for someone with a higher BMI. Either way, the advice is that you should take emergency contraception if you have had unprotected sex and you want to avoid unplanned pregnancy. ellaOne® has been clinically proven to be 2.5x more effective** than levonorgestrel when taken within 24 hours.
**verify at ellaone.co.uk/verify