Impact of Postnatal Head Circumference Growth in Normocephalic Infants Prenatally exposed to Zika Virus in Puerto Rico.

Objective: We aimed to describe the head circumference (HC) growth trends for non-microcephalic infants exposed to the Zika virus (ZIKV) in utero.

Methods: This was a medical record review of non-microcephalic neonates exposed to ZIKV whose mothers received prenatal care at the fetal evaluation unit (2015-2017). The mean HC values of babies from prenatal age to 1 year old were compared with the standardized values on HC growth charts.

Results: Sixty-three mother-infant pairs were included, and 56 infants (boys, 30%; girls, 70%) were evaluated. The mothers tested positive for ZIKV; their babies had a mean gestational age of 38 weeks (32-42) and a mean birth weight of 3,150 grams (1,190-4,220). The mean HC growth of the fetuses (19-34 weeks gestational age) placed them in the 25th percentile, increasing to the 50th percentile (according to the World Health Organization [WHO]). Compared with other growth charts (INTERGROWTH- 21st [International Fetal and Newborn Growth Consortium for the 21st Century] and Puerto Rico reference values), the mean HC grew in the 50th percentile at 18 to 30 weeks of gestational age, indicating normal growth in children from Zika-positive women. According to the WHO chart, the postnatal HCs of both the girls and boys reached the 75th and 50th percentiles, respectively.

Conclusion: Postnatal HC growth was normal. Results from this study suggest that infants exposed to ZIKV in utero can be normocephalic at birth. Therefore, the neurodevelopmental outcomes of such infants should be followed throughout childhood and adolescence, regardless of their HCs at birth.