Six per cent of Zika pregnancies result in birth defects: study
MIAMI, Florida (AFP) — About six per cent of babies born in the United States to mothers infected with the mosquito-borne Zika virus while pregnant were born with birth defects, US researchers said Thursday.
The report by the US Centers for Disease Control and Prevention was published in the Journal of the American Medical Association.
“CDC scientists used preliminary data from the US Zika Pregnancy Registry (USZPR) to estimate that six percent of completed pregnancies following Zika virus infection were affected by one or more birth defects potentially related to Zika virus infection during pregnancy,” said the report.
A total of 442 women with possible Zika infection had given birth by September 22, and 26 of those pregnancies, or six per cent, resulted in birth defects that may be linked to Zika.
Zika can cause babies to be born with malformed brains and unusually small heads, a condition known as microcephaly.
The rate of defects was higher — 11 per cent — among women who were infected with Zika in the first trimester of their pregnancies.
“Zika poses a real risk throughout pregnancy, but especially in the first trimester,” said CDC chief Tom Frieden.
“It’s critical that pregnant women not travel to areas where Zika is spreading.”
In four out of five cases, Zika causes no symptoms at all. Those who do report symptoms may have a rash, headache or body pain.
“The proportion of pregnancies with birth defects was similar for pregnant women who did or who did not experience symptoms, about six per cent in each group,” said the report.
Eighteen infants were diagnosed with microcephaly, representing four percent of the completed pregnancies.
Typically, the US prevalence of microcephaly is 0.07 per cent of live births.
Frieden said the study “shows that the rate of microcephaly and other fetal malformations related to Zika is similar among babies born in the United States – whose mothers were infected during travel to a dozen countries with active Zika transmission – to the estimated rate in Brazil,” where the first spike in cases of microcephaly was seen last year.
The report cautioned that its estimates are preliminary and could rise, particularly in light of recent research that showed some Zika babies appear normal at birth but go on to develop microcephaly in their first year of life.
