He was always pro-life. When he accepted the Libertarian party's offer to run for President under its banner, he made clear to them that the abortion issue was non-negotiable.
Ron Paul on Abortion
Voted NO on expanding research to more embryonic stem cell lines. (Jan 2007)
Voted NO on allowing human embryonic stem cell research. (May 2005)
Voted NO on restricting interstate transport of minors to get abortions. (Apr 2005)
Voted NO on making it a crime to harm a fetus during another crime. (Feb 2004)
Voted YES on banning partial-birth abortion except to save mothers life. (Oct 2003)
Voted NO on forbidding human cloning for reproduction & medical research. (Feb 2003)
Voted YES on funding for health providers who don’t provide abortion info. (Sep 2002)
Voted YES on banning Family Planning funding in US aid abroad. (May 2001)
Voted NO on federal crime to harm fetus while committing other crimes. (Apr 2001)
Voted YES on banning partial-birth abortions. (Apr 2000)
Voted NO on barring transporting minors to get an abortion. (Jun 1999)