Plan B works as an emergency contraceptive primarily by temporarily delaying or stopping ovulation, which is the release of an egg from the ovary. Without the release of an egg, sperm cannot fertilize it, so pregnancy is prevented
. Plan B contains a higher dose of the synthetic hormone levonorgestrel, which mimics the natural hormone progesterone. This surge in levonorgestrel interferes with the normal ovulation process
. Key points about how Plan B works:
- It is most effective when taken as soon as possible after unprotected sex, ideally within 72 hours (3 days), but can be taken up to 120 hours (5 days) after sex
- It does not terminate an existing pregnancy and will not affect implantation if fertilization has already occurred
- Plan B is a backup method and not intended for regular contraception use
- It does not protect against sexually transmitted infections
In summary, Plan B prevents pregnancy by delaying ovulation, thereby preventing fertilization. Its effectiveness depends on timing, working best when taken quickly after unprotected intercourse
