Plan B emergency contraception primarily works by delaying or preventing ovulation. Therefore, it is highly effective if taken before ovulation occurs. However, during ovulation, when the egg has already been released, Plan B is minimally effective or ineffective because it cannot stop fertilization or implantation after ovulation has happened. Detailed points:
- Plan B delays ovulation to prevent pregnancy but does not affect fertilization or implantation once an egg is released.
- If taken during ovulation, when the egg is available for fertilization, Plan B is unlikely to prevent pregnancy.
- It is most effective when taken as soon as possible after unprotected intercourse and ideally before ovulation.
- For emergency contraception needed during or after ovulation, alternatives like the copper IUD are recommended, as they can prevent pregnancy through mechanisms beyond ovulation delay.
In summary, Plan B does not work effectively if taken during ovulation because its primary mechanism is to delay ovulation, which is already occurring or completed during this time.
