The U.S. government is ramping up its warnings about the Zika virus epidemic for both men and women.

On Friday, the Centers for Disease Control (CDC) issued broad new recommendations cautioning pregnant women to contemplate postponing travel to 11 Southeast Asian countries where the mosquito-borne virus is spreading, and fortified its warnings for men who are planning to start a family.

“CDC recommends pregnant women should consider postponing nonessential travel to Southeast Asia countries with reports of Zika virus infection from local transmission or related to travel to those countries, and those countries with adjacent borders where limited information is available to fully evaluate risk of Zika virus infection,” wrote the agency in an update.

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The relevant nations are: Brunei; Myanmar; Cambodia; Indonesia; Laos; Malaysia; Maldives; the Philippines; Thailand; Timor-Leste (East Timor); and Vietnam.

While people living in those countries may have developed an immunity to the virus, which can cause severe birth defects in infected pregnant women’s children, travelers may not enjoy similar protection, the CDC explained. Thai health officials recently confirmed that two cases of microcephaly (abnormally small heads) in newborns have been linked with the Zika virus in that country.

But the guidance also highlighted new warnings for men, who can transmit the virus (which has relatively mild health effects in adults) via sexual intercourse to their partners. And if a couple is planning on getting pregnant, that can spell trouble for the unborn child.

The CDC had originally warned men who had not developed active Zika symptoms but still may have contracted the virus by visiting an affected region to put off conception for eight weeks; now, the agency has lifted that timeframe to six full months.

Regulators’ heightened caution comes on the heels of reports suggesting that Zika can actually remain in semen for much longer than expected.

Congress finally approved a bill funding the anti-Zika fight in U.S. states and territories late Wednesday, including provisions to fund vaccine research and mosquito control efforts. It took lawmakers 233 days to pass the emergency appropriations requested by President Obama in February.