Biosecurity

Rate of birth defects in Zika pregnancies 20 times higher than in pre-Zika years, CDC says

Pregnancies of women in the United States infected with the Zika virus are about 20 times more likely to result in babies with certain birth defects, compared with the prevalence of these birth defects before the Zika epidemic swept through the Americas, according to a report released Thursday.

Researchers at the Centers for Disease Control and Prevention are trying to determine how common these birth defects, such as microcephaly, brain abnormalities, eye defects and central nervous system problems, were in the years before the Zika outbreak. Although a Zika infection during pregnancy is linked to a distinct pattern of birth defects, those abnormalities are not unique to Zika. Genetic factors and other viral infections may also cause these birth defects, although in many cases the causes are unknown, experts say.