SUMMARY: Around 14 percent of babies whose mothers contracted Zika while pregnant ended up with a birth defect, developmental abnormality, or both, according to a report released by the US government today
(August 7). Some of the symptoms didn't show up right away when the babies were born but emerged in later
testing. "The full range of long-term health problems
caused by Zika will remain unknown until these babies
mature," according to a summary of the report from the Centers for Disease Control and Prevention (CDC).
EXPERIMENT: The agency collected health data on 1,450 babies at least one year old who were exposed to
Zika in utero and born in a US territory. Six percent of the children had a Zika-associated birth defect, but
others' symptoms showed up later in life. Among 822 babies who did not have a birth defect, 14 had a brain
abnormality that was revealed in neuroimaging.
CONCLUSION: “That happened because their brain was not grovmg and developing properly" due to the
virus, Margaret Honein, director of the Division of Congenital and Developmental Disorders at the CDC, tells
NPR. In the US and its territories, reports of Zika infections tapered off at the beginning of 2017, with very few
cases popping up since then but outbreaks may re-emerge.

11. What is the independent variable?
A. Pregnant women with Zika virus
B. Age of babies
C. Number of Zika virus infections
D. Health data on babies born to mothers with Zika virus