Of the 250 pregnant women who had confirmed Zika infection in 2016, 24 â or about 1 in 10 of them â had a fetus or baby with Zika-related birth defects, according to a new Vital Signs report from the Centers for Disease Control and Prevention (CDC). This report is the first to provide the analysis of a subgroup of pregnant women in the U.S. with clear, confirmed test results of Zika virus infection.