The new guidance is double the time experts had previously advised
The World Health Organisation (WHO) says people returning from areas hit by Zika should wait for at least eight weeks before trying for a baby.
The new guidance is double the four weeks the organisation had previously been advising.
The virus - which has been linked with birth defects - is a particular issue in Brazil.
Experts at the WHO also say women should defer getting pregnant for six months if their male partner has shown symptoms of Zika.
Spokesman Christian Lindmeier, quoted by Reuters, said the new advice takes into account "reflect what we have learned about Zika disease and its complications".
Earlier this month, WHO said cancelling or changing the location of the upcoming Olympics in Rio de Janeiro "will not significantly alter the international spread of Zika virus".
Pregnant women have already been advised not to travel to Rio, but the WHO has said the risk of Zika will lessen in August because it is winter in Brazil.
Zika has been linked to serious birth defects including microcephaly - where babies are born with abnormally small heads and underdeveloped brains.
It has also been linked to Guillain-Barre syndrome and Acute Disseminated Encephalomyelitis which affect the nervous system.
Nearly 1,300 babies have been born in Brazil with microcephaly since the mosquito-borne Zika began circulating there last year.
The majority of those infected with the virus have no symptoms, but it can cause a mild illness with symptoms including rashes, fever and headaches.