The CDC says that the level of risk for Zika virus infection in the 11 countries in the travel advisory is unknown, but "it is likely lower (but not zero) than in areas where Zika is newly introduced and spreading widely".
The World Health Organisation (WHO) on Friday urged countries across the Southeast Asia region to continue taking decisive action against Zika virus as two new cases of Zika-related microcephaly were confirmed in Thailand.
The CDC now only allows for testing pregnant women or symptomatic individuals if they live in or have recently traveled to an area with Zika or have had sex with a partner who lives in or recently traveled to an area with Zika.
More than 25,000 cases of Zika have been reported in the US and its territories, including about 2,200 pregnant women.
The CDC said for Singapore, pregnant women "should not travel" there.
Thailand is not the only country in Asia to report cases of Zika.
Microcephaly is an effect of the Zika virus which can be passed from a pregnant woman to her unborn baby.
Following the epidemic in Brazil, Asia was identified as being at high risk of Zika virus transmission based on an analysis of climatic conditions and the propensity for travel.
In other developments, Thailand confirmed two Zika-linked microcephaly cases, its first, and CDC researchers published a case series on USA children who contracted Zika during travel, suggesting that their infections are usually mild, as they are for most adults.
When traveling to areas where Zika virus or other viruses spread by mosquitoes have been reported, use insect repellent, wear long sleeves and trousers, and stay in places with air conditioning or that use window and door screens. It also warned pregnant women against nonessential travel to the Maldives. These risks make testing pregnant women a priority, since they have a limited time to make decisions about their pregnancy, further limited by the several weeks it can take to confirm a Zika diagnosis.
Zika causes only mild symptoms in most, including fever, sore eyes and a rash.
That's because every person who brings the virus back into their country and gets bitten by an Aedes aegypti mosquito could be starting a local outbreak, which is what is happening now in Southeast Asia and in Florida in the United States. That precaution applies to both male and female partners of the pregnant woman and includes male and female condoms, sex toys and dental dams for any vaginal, anal or oral sex.
Microcephaly in babies can lead to respiratory problems and lifelong difficulties, including intellectual impairment. The virus has been linked to serious birth defects, including microcephaly.