Scientists Get Closer to Understanding Zika Birth Defects

Health officials have said for some time now that they are confident that Zika causes the birth defect microcephaly. Precisely how the virus does that remains unclear. But studies published Wednesday add to the picture, showing how the virus can multiply in the placenta and reach the fetus.

In a study published in the journal Cell, researchers used mouse models to see how a Zika infection behaves during pregnancy. Researchers at Washington University School of Medicine in St.