Language delay was associated with a smaller head circumference at birth in asymptomatic infants prenatally exposed to the Zika virus

AIM: Our aim was to analyse 12-month outcomes of children who were prenatally exposed to the Zika virus and asymptomatic at birth. METHODS: This was an observational, exploratory study of infants exposed to the Zika virus during gestation and born between March 2016 and April 2017 without congenital Zika syndrome. They were followed until the age of 22 months. The outcome measure was neurodevelopment at 12 months of life, which was evaluated with the Bayley Scales of Infant and Toddler Development, Third edition (Bayley-III). The scores were adjusted for maternal education and prematurity. RESULTS: A total of 96 infants were included in the study and 35.4% scored below the normal range in at least one Bayley-III domain. The majority (91.2%) of the infants with delayed scores presented with language delay, which was not associated with the gestational age at exposure. Receptive language was more affected by exposure than expressive language (27.0% vs 19.8%). There was a direct, and significant, association between the head circumference Z-score at birth and language delay. CONCLUSION: Language delay was associated with a smaller head circumference at birth in infants prenatally exposed to the Zika virus and born asymptomatic. This may indicate future learning difficulties.