Zika infection in the third trimester of pregnancy may not be as dangerous for a developing fetus as infection earlier in pregnancy, scientists from Colombia and the Centers for Disease Control and Prevention reported Wednesday.
No cases of microcephaly or other obvious birth defects were seen among the babies born to a group of 616 Colombian women who contracted Zika in their third trimester, the researchers reported in an article published by the New England Journal of Medicine.
In a more concerning finding, the scientists also reported that four women who had no symptoms of a Zika infection during pregnancy gave birth to babies who had microcephaly. The newborns were confirmed to have Zika virus in their systems.
One of the many unanswered questions about Zika is whether women who are infected but don’t have any symptoms run the same risk of having a baby with microcephaly — an abnormally small head — as women who have symptoms of the infection.
The article published Wednesday doesn’t indicate if the risk is the same, but it does make clear that pregnant women who have no symptoms may still give birth to a Zika-affected infant.
It is estimated that four of five people infected with Zika virus are asymptomatic.