The UN health agency is changing its advice to travellers returning from areas facing a Zika virus outbreak, saying both men and women should now practice safe sex or abstinence for six months.
The World Health Organisation's guidance applies to all travellers, whether or not they show symptoms of the virus.
Read: Report hints Zika can spread through oral sex
The organisation's previous guidance in early June was for only men without symptoms to use condoms or abstain from sex for eight weeks after returning from areas with Zika epidemics.
The disease is mostly transmitted by mosquitoes.
A strain of Zika now circulating in Latin America has been proven to cause brain and head abnormalities in newborns. WHO says men and women living in such areas should make an "informed choice about whether and when to become pregnant".
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Zika may also cause stillbirth