eli5: How do emergency contraceptives, like Plan B, work?

Question

eli5: How do emergency contraceptives, like Plan B, work?

In: 8

Answer 1

Emergency contraceptives typically contain one or a combination of hormones that are the same as used in daily birth control only in a larger dose. This prevents the egg from being released, or if it’s already been released, it slows the movement of the egg and the sperm making it less likely that they’ll encounter one another, and finally, failing that, it will prevent the fertilized embryo from implanting into the wall of the uterus and growing any further.

Answer 2

If no egg has been released, its release is delayed. If an egg has been released, menstruation is hastened. In any case, the chain reaction that leads to pregancy is (probably) disrupted.