Zika Resource Center
Zika Resource Center
July 17, 2019
2 min read

One-third of children exposed to Zika in utero show neurological problems

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Photo of Karin Nielsen-Saines
Karin Nielsen-Saines

Almost a third of children aged 3 years and younger who were exposed to Zika virus during their mother’s pregnancy had below-average neurological development, a recent study published in Nature Medicine suggests.

“Long-term follow up is needed for children who are exposed to maternal infections duringpregnancy, especially viruses that are novel and others that are known to be teratogenic,” lead author Karin Nielsen-Saines, MD, MPH, the study’s lead author and a professor of clinical pediatrics at the David Geffen School of Medicine at the University of California, Los Angeles, told Infectious Diseases in Children. “Repercussions of in utero infection may not be apparent at birth, they can manifest later, and following neurodevelopment and neurosensory function in the first years of life all the way through the early school years is important.”

The study examined the neurological development of 216 infants who were followed since the time of PCR-confirmed maternal Zika virus infection in pregnancy during the 2015-2016 epidemic in Rio de Janeiro. Researchers measured neurodevelopment in 146 children using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III), and the remaining 70 were tested using the less detailed Hammersmith Infant Neurological Evaluation.

According to the researchers, 31.5% of children between the ages of 7 and 32 months were found to have below-average neurodevelopment and/or abnormal eye or hearing assessments. Of those assessed via the Bayley III, 12% measured below –2 s.d. (score <70; a score of 100 ± 2 s.d. is the range) in at least one domain — cognitive, language or motor. Language was the most affected, the researchers said, with 35% of the 146 children measured by the Bayley-III scoring below average.

Nielsen-Saines and colleagues’ research expands on a 2018 study that revealed that 14% of 131 children exposed to Zika during their mothers’ pregnancies had severe neurodevelopmental delay or sensory organ dysfunction, or both.

“Some children with more subtle but still abnormal neurologic exams in infancy did better than expected in terms of development 2 years later, whereas others who seemed normal at birth had poor developmental scores in the second or third year of life,” Nielsen-Saines said. “The bottom line is that it’s not possible to predict how all Zika-exposed children will fare in the future.” – by Eamon Dreisbach


Moreira EL, et al. N Engl J Med. 2018;doi:10.1056/NEJMc1800098.

Nielsen-Saines K, et al. Nat Med. 2019;doi:10.1038/s41591-019-0496-1.

WHO. Zika virus. https://www.who.int/news-room/fact-sheets/detail/zika-virus. Accessed July 15, 2019.

Disclosures: The authors report no relevant financial disclosures.