Romney explained that he wrote an op-ed in The Boston Globe explaining his personal opposition to abortion.
The Republican candidate has this cycle expressed his opposition to abortion, with the exception of cases of rape.
Rape is not an exception in the Republican Party platform adopted in Tampa this summer, nor was it an exception Rep. Paul Ryan - who in August joined Romney's ticket - supported, though Ryan said he supports Romney's position on the issue.
The issue of abortion was briefly in the spotlight earlier this year when Rep. Todd Akin, a Missouri Republican seeking to unseat Democratic Sen. Claire McCaskill, made controversial comments about "legitimate rape."
He claimed in a television interview that "legitimate rape" rarely resulted in pregnancy, saying that "the female body has ways to try to shut that whole thing down."
Romney distanced himself from those comments and called for Akin to exit the race.