Mexico's Health Ministry announced that six pregnant women have been infected with the mosquito-borne Zika virus that causes a severe birth defect.
The women are among 80 total Zika cases in Mexico, with more than half of them reported in the southern impoverished state of Chiapas, the ministry said.
Among the pregnant women, four are in Chiapas, one in the southern state of Oaxaca and another in Veracruz in the east.
But rising anxiety about the virus is driven by its strongly suspected link to microcephaly, which causes babies to be born with abnormally small heads, and the Guillain-Barre syndrome, a severe neurological disorder.
Brazil has been most affected by the outbreak that has spread rapidly through Latin America and the Caribbean, with 1.5 million people in the country infected since early 2015.