Zika-linked abnormalities that occur in human fetuses are more extensive -- and severe -- than previously thought, and that other birth defects are more common than microcephaly, when babies are born with very small heads.
"This means that microcephaly is not the most common congenital defect from the Zika virus," said the study's senior author Karin Nielsen, Professor at David Geffen School of Medicine, University of California, Los Angeles.
‘Zika infection during pregnancy is associated with fetal death, fetal growth restriction, and a spectrum of central nervous system abnormalities.’
The absence of that condition does not mean the baby will be free of birth defects, because "there are problems that are not apparent at birth" and such difficulties may not be evident until the age of six months, she added.
The study, published in the New England Journal of Medicine, suggests that damage during fetal development from the mosquito-borne virus can occur throughout pregnancy.
"These are sobering results," Nielsen said. The study was based on a sample size of 345 women in Rio de Janeiro, Brazil, who were enrolled from September 2015 through May 2016.
From there, the researchers evaluated 125 women infected with Zika and 61 who were not infected with the virus who had given birth by July 2016. There were nine fetal deaths among women with Zika infection during pregnancy, five of those in the first trimester.
Fetal deaths or abnormalities in the infants were present in 46 percent of Zika-positive women, contrasted with 11.5 percent of Zika-negative women. The study found that Zika infection during pregnancy is associated with fetal death, fetal growth restriction, and a spectrum of central nervous system abnormalities.
"Our data show that the risk of severe adverse pregnancy and infant outcomes after maternal Zika infection was substantial," the authors wrote.