A study published in the Journal of the American Medical Association on December 13, 2016 provided insight into the degree of harm to babies from exposure to the Zika virus in pregnancy. In the study, the Centers for Disease Control and Prevention (CDC) and state health department scientists report:
- 6% of babies from pregnancies with Zika virus infection have one or more birth defects; 11% if the mother was infected during the first trimester of the pregnancy.
- The proportion of pregnancies with birth defects was similar for pregnant women who did or who did not have symptoms, about 6% in each group.
- Most of the affected babies in the study had the well-recognized microcephaly, but some had other structural brain differences.