Pregnant mothers infected with the Zika virus are 20 percent more likely to bear children with specific birth defects such as microcephaly, a new study revealed.

Researchers from the Centers for Disease Control and Prevention found that the birth defect risk among pregnant women with Zika virus is now 20 times higher compared to the time before the Zika epidemic began in the Americas. These findings strongly emphasize the devastating effects of this mosquito-borne infection on pregnant women and their babies.

Birth Defect Risks

In 2015, the Zika virus began to spread throughout South America, causing a sudden spike in cases of microcephaly among newborns. Thousands of babies whose moms were infected with Zika had been born with smaller-than-normal heads and underdeveloped brains.

In the study, experts sought to determine how common birth defects had been before the spread of Zika virus. The list of birth defects included in the study are microcephaly, brain abnormalities, central nervous system problems, and eye defects, which are not exclusive to Zika. Other genetic factors and viral infections may also cause them.

Researchers examined 2013-2014 data taken from North Carolina, Georgia, and Massachusetts, all of which kept detailed track of birth defect records. Researchers believe birth defect incidences in these areas are representative of the whole country.

The study found that three in every 1,000 infants had birth defects when they were born during the pre-Zika period.

Experts then compared the baseline number with that of birth defect cases linked to Zika, which has been listed at the U.S. Zika Pregnancy Registry.

Statistics show that 747 infants and fetuses had been born with one or more birth defects in the three states. Brain abnormalities such as microcephaly were the most common illness.

What's more, when researchers looked at microcephaly and brain abnormality cases alone, what they saw was a 30 percent higher prevalence compared to before Zika spread in the United States, said Margaret Honein.

However, Honein said it's still too early to provide a precise estimate for the additional risk of birth defects linked to Zika virus.

"I don't have that level of precision, but there is strong evidence of a major increase in risk," said Honein, who is the chief officer at the CDC's birth defects branch.

How To Prevent Zika Virus Infection

The CDC report suggests the critical importance of preventing Zika virus infections during pregnancy. Honein said pregnant women should not travel in places where the virus is endemic. If they have to, they should consult their doctors about taking the necessary steps to protect themselves against mosquito bites and sexual transmission, she added.

Details of the study are featured in the Morbidity and Mortality Weekly Report of the CDC.

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