Emergency Contraception (EC), sometimes referred to as the morning after pill, is birth control that can be used after unprotected sex in order to prevent pregnancy. EC comes in two forms: pill (ella and other brands like Plan B) and the ParaGard IUD. EC prevents pregnancy by stopping ovulation, fertilization, or, possibly, implantation.
The hormones in the pill versions of EC disrupt hormone production in the ovaries. This will delay ovulation if it has not already occurred and will make the uterine lining unsuitable for implantation of an egg if fertilization has occurred.
The ParaGard IUD prevents pregnancy due to the copper material present in the IUD. Sperm does not like copper, and having copper present makes it harder for sperm to swim well enough to reach an egg and fertilize it.
EC will not affect an existing pregnancy and it will not cause an abortion. EC is not the same as RU-486 (Mifepristone), the early option pill that is given to induce a medical abortion after a person is already pregnant.