The worries that tug at a pregnant woman’s mind tend to shift in time. As weeks and months go by, new concerns invariably crop up.
But for many women, the end of the first trimester brings with it a significant degree of relief: That’s the point at which the risk of miscarriage drops dramatically. It’s also a key milestone following a critical phase in fetal development.
On top of that, some diseases, like rubella, which can be catastrophic to fetuses whose mothers fall ill in the first trimester, are less serious if a woman is infected later in pregnancy. As a result, conventional wisdom focuses on the first trimester as the most vulnerable time for a fetus.
But that doesn’t seem to be the case with the Zika virus. A new study, published Wednesday in The Lancet, finds evidence that the virus can still cause devastating brain defects among newborns whose mothers were infected in their last trimester.
The finding is alarming for several reasons. For one, it underscores the risk of Zika to pregnant women at any stage. This builds on earlier research, published in the New England Journal of Medicine in March, that found Zika can cause “grave outcomes” for fetuses well past the 30-week mark.