It also reinforces the understanding that women infected in the early stages of pregnancy face the greatest risk. The Zika virus causes only a mild and brief illness, at worst, in most people. But health officials say Zika can cause other birth defects, too. That study estimated risk of microcephaly at 1 per cent for pregnancies in which the mother was infected in the first trimester. The largest study to ever look at the question says the risk of one especially severe type of birth defect is "substantial" — in the range of 1 per cent to 14 per cent.

Source: CBC News May 25, 2016 16:03 UTC