ABOARD THE PAPAL PLANE — Pope Francis has suggested that women threatened with the Zika virus could use artificial contraception, saying there’s a clear moral difference between aborting a fetus and preventing a pregnancy.

Francis was asked Wednesday en route home from Mexico if abortion or birth control could be considered a “lesser evil,” when confronting the Zika crisis in Brazil, where some babies have been born with abnormally small heads to Zika-infected mothers.

The World Health Organization has declared a global health emergency over the Zika virus and its suspected links to birth defects. The virus has been reported in at least 34 countries, many of them in Central and Latin America. WHO and the U.S. Centers for Disease Control and Prevention have advised pregnant women to consider delaying travel to Zika-infected countries.

The explosion of Zika cases has prompted some governments in Latin America to urge women to avoid getting pregnant and has fueled calls from abortion rights groups to loosen the strict anti-abortion laws in the overwhelmingly Catholic region.

But Francis excluded abortion absolutely from the debate.

“Abortion isn’t a lesser evil, it’s a crime,” he told reporters. “Taking one life to save another, that’s what the Mafia does. It’s a crime. It’s an absolute evil.”

Francis, however, drew a parallel to the decision taken by Pope Paul VI in the 1960s to approve giving nuns in Belgian Congo artificial contraception to prevent pregnancies because they were being systematically raped.