INTRODUCTION
Zika virus (ZIKV) infection is particularly important when acquired
during pregnancy. Perinatal adverse outcomes have been linked to
pregnancy losses or fetal neurological damage1,2.
Adverse effects following maternal ZIKV infection have been previously
reported, but there is limited data available from large cohorts of
ZIKV-infected mother-infant pairs. A wide variety of inclusion criteria
and definitions of adverse outcomes have been used for prevalence
estimates of abnormalities ranging widely from
5-46%3-13. Further, the impact of the gestational age
of maternal infection on the risk of fetal abnormalities has not yet
been fully defined.
Although the epidemic phase of ZIKV infection is over, there is still
interest on enhancing knowledge about mother-to-child transmission and
its consequences to the infant, since the endemic spread is continuing
globally14 and could reemerge as a public health
problem due to socioeconomic or climatic changes15.
In 2016, a large cohort of ZIKV-infected symptomatic pregnant women and
their infants was composed in Ribeirão Preto metropolitan region,
Brazil. Our primary objective was to investigate the prevalence of
adverse pregnancy and early neonatal outcomes with an emphasis on
pregnancy losses, microcephaly, and Congenital Zika Syndrome (CZS) as
functions of the gestational age of maternal infection. A subset of
infants had received an additional specialized evaluation within three
months of life, allowing us to estimate the probability of occurrence of
early-presenting occult/mild end-organ disease among infants who had not
been identified affected at birth.