The primary mechanism by how the morning-after pill works is to delay or prevent ovulation, hence taking the pill after ovulation will mean the pill is much less effective. However, I will generally still advise my patient to take the pill to prevent any unwanted pregnancy if there was unprotected sex because of the following reasons:
- We can estimate when ovulation happens, which is about 14 days after your period for a usual menstrual cycle of 28 days, but we are unable to say for certainty when it actually occurs. As such, there is always a chance that your estimation of your ovulation phase is inaccurate, leading to the possibility of pregnancy.
- Other factors like stress, exercise, etc can affect your hormonal balance and lead to inaccuracies in your ovulation as well
In view of the above, if there was unprotected intercourse, I would still recommend the morning-after pill which should be taken as soon as possible, up to a maximum of 5 days after intercourse, in the case of Ella. If menses is missed, a pregnancy test should still be performed.
If long term contraception is required, do speak to your family physician regarding other contraceptive options.