What exactly is the risk for birth defects in children born to pregnant women infected with Zika virus?
A new analysis led by researchers at the Centers for Disease Control and Prevention (CDC) provides more information towards answering this question, just as the scientific community begins to learn more about how the mosquito-borne virus affects mothers and their babies. The findings
of the CDC study were published in the December 15 issue of the Journal of the American Medical Association
), and covered by Contagion
the same day.
In all, the CDC researchers found that, among pregnant women in the United States with completed pregnancies and laboratory evidence of possible recent Zika infection, 6% had a fetus or infant with evidence of a virus-related birth defect. Furthermore, among women with first-trimester Zika infection, 11% had a fetus or infant with a birth defect. Perhaps, most alarmingly, of the 26 affected fetuses or infants included in the analysis, 4 had microcephaly and no reported neuroimaging, while 14 had microcephaly and brain abnormalities; the other 4 had brain abnormalities without microcephaly. The authors used data from 442 completed pregnancies reported to the US Zika Pregnancy Registry between January 15 and September 22, 2016 to derive their estimates.
At present, of course, CDC guidelines recommend Zika virus testing for women with possible exposure during pregnancy, even if they are asymptomatic. But even this level of vigilance may not be enough to ensure the health of infected mothers and their children. Indeed, in a separate commentary
published on the same day by The New England Journal of Medicine
), two of the physicians involved in the CDC analysis reference the response to findings regarding infant outcomes “associated with thalidomide use and rubella infection” and call for a similar global response to Zika virus. “What is clear is that the devastating effect of [Zika virus] infection is not limited to infection early in pregnancy and that damage to the fetal brain can occur even with infection in the second and third trimesters,” they write. “These findings are sobering and emphasize the public health urgency of planning for the needs of children and families affected by the congenital Zika syndrome… Countries experiencing a major increase in the total number of children with structural birth defects need to prepare for clinical, public health, social, and educational demands.”