Birth Outcomes Related to Prenatal Zika, Dengue, and Other Flavivirus Infections in the Zika en Embarazadas y Niños Prospective Cohort Study in Colombia

Zika virus (ZIKV) infection in pregnancy is associated with severe abnormalities of the brain and eye and other adverse outcomes. Zika en Embarazadas y Niños was a prospective cohort study conducted in multiple Colombian cities that enrolled pregnant women in their first trimester. Specimens collected from pregnant women ( n = 1,519) during February 2017–September 2018 and their infants ( n = 1,080) during June 2017–March 2019 were tested for prenatal ZIKV infection by nucleic acid amplification tests or IgM antibody testing. Zika virus infection in pregnancy was present in 3.2% of pregnant women (incidence rate [IR] per 1,000 person-months = 5.9, 95% CI: 4.3–7.8). Presumptive ZIKV infection was present in 0.8% of infants (IR = 1.6, 95% CI: 0.7–2.9). Five percent of infants with prenatal ZIKV exposure or infection presented with Zika-associated abnormalities; 4.7% were small for gestational age. Understanding the risk of ZIKV infection during pregnancy and associated adverse outcomes can help inform counseling efforts.