Pope Francis has suggested it is acceptable to use artificial contraception methods in countries affected by the Zika virus.
"Avoiding pregnancy is not an absolute evil," he told reporters en route to Rome following his five-day trip to Mexico.
He cited Pope Paul VI's decree in the 1960s that allowed nuns serving in Africa to use contraception due to the threat of rape.
He said, "In certain cases, as in this one, such as the one I mentioned of Blessed Paul VI, it was clear."
But he maintained the church's stance against abortion calling it "an absolute evil".
Earlier this month, the Centers for Disease Control and Prevention advised men who have been to an area with Zika virus to abstain from sex or use condoms. It added that men with pregnant partners should abstain or use condoms for the duration of her pregnancy.
Experts suspect Zika could cause microcephaly, a condition in which babies are born with unusually small heads because the brain has not developed properly or has stopped growing.
The Zika virus is becoming a major problem in Latin America, particularly in Brazil, which reports more than 4,300 suspected cases of microcephaly.