Baseline Prevalence of Birth Defects Associated with Congenital Zika Virus Infection — Massachusetts, North Carolina, and Atlanta, Georgia, 2013–2014

Abstract

© 2017, Department of Health and Human Services. All rights reserved. What is already known about this topic? Zika virus infection causes serious brain abnormalities; however, the birth defects observed are not unique to congenital Zika virus infection, and the full range of effects of congenital Zika infection is not known. What is added by this report? CDC used data from population-based birth defects surveillance programs in Massachusetts, North Carolina, and Atlanta, Georgia, to retrospectively assess the prevalence of birth defects during 2013-2014 that met the surveillance case definition for birth defects potentially related to Zika virus infection, before introduction of Zika virus into the United States. After introduction of Zika virus, the proportion of infants and fetuses with birth defects born to mothers with laboratory evidence of possible Zika infection reported by the US Zika Pregnancy Registry during January 15-September 22, 2016, was approximately 20 times higher than the prevalence of potentially Zika-related birth defects among pregnancies during the pre-Zika years. What are the implications for public health practice? Data on birth defects in the pre-Zika years serve as benchmarks to direct rapid ascertainment and reporting of birth defects potentially related to Zika virus infection. The higher proportion of these defects among pregnancies with laboratory evidence of possible Zika virus infection supports the relationship between congenital Zika virus infection and birth defects.