The morning after pill works by delaying ovulation which means that no egg will be released and any lingering sperm will have nothing to fertilise.
Sperm can survive in the female reproductive system for up to five days, so even if you don’t think you’re about to ovulate you could still become pregnant if you ovulate up to five days after unprotected sex.
“If you have had unprotected sex, then it’s understandable that you may be worried and anxious about getting pregnant. However, taking the morning after pill as soon as possible can reduce your risk of pregnancy,” says Deborah Evans**, a pharmacist with over 30 years experience.
No other morning after pill is more effective than ellaOne. A clinical trial found that there is only a 9 in 1000 chance that you could get pregnant if you take ellaOne within 24 hours after unprotected sex.
You can also get a copper intrauterine device (IUD) fitted as a form of emergency contraception if you can get it fitted within 120 hours of unprotected sex. As you have to wait for an appointment to get this fitted by a doctor or nurse, you may be advised to also use an emergency contraceptive pill for the best chance of preventing pregnancy.