This depends on which phase of your cycle you are in at the time of a contraceptive breakdown. The likelihood of getting pregnant is the highest just before ovulation7.
Not sure if you’re still pre-ovulating or already post-ovulating in your current cycle? You are not alone in this, because hardly any woman can say exactly. But one thing is certain: the morning-after pill can postpone ovulation if it has not yet occurred.
Also, for emergencies: If you don’t want to get pregnant, you should take the morning-after pill – regardless of the phase of your cycle. Then you are on the safe side. The earlier you take it, the greater the chance that it can postpone your ovulation8.The morning-after pill with the active ingredient ulipristal acetate is still effective in the most fertile phase of the cycle until shortly before ovulation, when the risk of pregnancy is highest9.