Yesterday, the World Health Organization issued a warning advising pregnant women to not travel to areas with Zika, and specifically, advised travelers to take precautions against the mosquitoes that spread the virus in anticipation for the Rio de Janeiro Olympics.

In its statement, the U.N. health agency also said that since Zika can also be spread sexually, pregnant women should abstain from sex or practice safe sex with anyone who has recently returned from areas with outbreaks.  Zika has now been proven to cause a range of  birth defects. Symptoms include babies being born with abnormally small heads.

Also, this week, a Canadian professor called for the Olympics to be postponed altogether or moved to another area of the world because of the epidemic, and claimed that the games would lead to a lot of new babies born with malformations.

h/t Time