Dec 23 (Reuters) - The U.S. Food and Drug Administration on Friday changed the label for the emergency contraception known as Plan B One-Step to make clear that the pill does not alter the course of an existing pregnancy.

The consumer information distributed with the morning after pill known as Plan B One-Step, which has been available over the counter for everyone since 2013, now makes clear its mechanism of action does not alter the implantantion of an egg.

It explains that Plan B One-Step works before the release of an egg from the ovary and as a result, usually stops or delays the release of an egg.

Contraception has come under renewed pressure in the United States after the Supreme Court in June overturned the landmark 1973 Roe v. Wade ruling that recognized the constitutional right to an abortion and legalized it nationwide.

The FDA also issued an updated question-and-answer section on its website, where the question "Is Plan B One-Step an abortifacient (causing abortion)" is answered with "No."