The Zika virus, which may cause a birth defect called microcephaly, has been found in 20 Latin American countries as well as the south Paciific country of Samoa. Carried by mosquitoes, doctors and researchers fear it will spread even further.

If pregnant, beware of travel to countries with Zika virus https://t.co/epv6mSO78x @NewsHour

— PBS (@PBS) January 23, 2016

NBC News reports the U.S. Centers for Disease Control and Prevention reiterated its warning on Friday that pregnant women shouldn’t travel to any of the countries where the Zika virus has spread.

A team of Brazilian researchers who studied the Zika virus say 35 babies whose mothers were diagnosed with the virus were born with microcephaly. Microcephaly causes underdeveloped brains and heads.

What you need to know about Zika virus, a tropical infection new to the Western Hemisphere https://t.co/OjM2ZbIa6c

— The New York Times (@nytimes) January 23, 2016

There is much left to learn about the Zika virus, but in the meantime pregnant women should definitely heed the CDC’s warning.

Those countries where people have test positive for the Zika virus are Barbados, Bolivia, Brazil, Colombia, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, and Venezuela. Samoa, in the south Pacific, has just recently reported Zika for the first time.

VIDEO: Tackling Brazil's Zika virus crisis https://t.co/ISMe7PSzYU

— BBC News (World) (@BBCWorld) January 23, 2016

Are you pregnant? Have you discussed the Zika virus with your obstetrician?