The move came one day after he announced he would not seek re-election in November 2018.
"This afternoon I received a letter of resignation from Congressman Tim Murphy, effective October 21," House Speaker Paul Ryan said in a statement.
"It was Dr. Murphy's decision to move on to the next chapter of his life, and I support it."
Murphy, an eight-term congressman from Pennsylvania, has been popular with members of the pro-life movement, and recently sponsored legislation that criminalizes most abortions after the 20th week of pregnancy.
The measure passed the House on Tuesday largely along party lines, and a companion bill was introduced to the Senate on Wednesday.
The bill is unlikely to pass the Senate, where Democratic blocking tactics could derail it.
Murphy, 65, acknowledged last month that he had an extramarital affair with Shannon Edwards, a psychologist who worked with him on mental health legislation.
On Tuesday the Gazette reported that Edwards sent Murphy a text message in January that excoriated him for an anti-abortion statement on his Facebook account.
"And you have zero issue posting your pro-life stance all over the place when you had no issue asking me to abort our unborn child just last week when we thought that was one of the options," Edwards wrote about an apparent pregnancy scare, the Gazette reported.
Another Republican pro-life congressman, Scott DesJarlais, faced a similar abortion scandal in 2012, but he remains in Congress.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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