Birth defects occur in 1 in 10 pregnancies with first trimester Zika infection
Analysis of pregnant women helps firm up numbers, timing of virus’s effect on fetuses
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2016/12/121416_mr-zikastat_free.jpg?fit=860%2C460&ssl=1)
DANGER ZONE Zika infection in the first trimester is especially risky, according to new results from an analysis of Zika-affected pregnancies in the United States.
wavebreakmedia/Shutterstock