New estimates have shown that around 1.65 million women in Latin America could become infected with Zika while they are pregnant, with Brazil carrying the highest number of all. This comes from new research from the University of Southampton in the United Kingdom and the University of Notre Dame.
The team at the two universities calculated the number of women who get pregnant who give birth to a full-term baby. They then estimated that the Zika virus outbreak would last another two to three years and settled on the 1.65 million number. However, this is the upper limit of what is possible, stated lead authors on the study.
Alex Perkins, a co-author of the study, said that women in poorer areas are more likely to be infected with the virus. This is because they are less likely to have screens on their windows or air conditioners, two factors that help keep mosquitoes out of homes.
Perkins also said in a statement:
“We think these projections may be pretty good for a location where Zika shows up and starts an epidemic, but at the same time we acknowledge that due simply to random chance and the fact that some places are relatively isolated and sparsely populated, the virus won’t make it to every single corner of the continent.” 
These statistics are important, as while Zika may be asymptomatic in adults, it can cause a wide range of health problems amongst fetuses. Zika has been linked to microcephaly, a developmental disorder in which the child’s head is smaller than that of other children. Aside from being a cosmetic issue, microcephaly can contribute to serious health and developmental issues, which can severely delay overall development and halt speech and walking.
The overall extent of birth defects Zika can cause is not known. It is theorized that Zika may also cause hearing and vision problems to children born to mothers infected with the virus later on in life, though currently this is speculation.
In Brazil alone, there have already been 1600 recorded cases of microcephaly. 
 NBC News