Procedures and Definitions
Maternal demographic, clinical, laboratory, obstetrical, and neonatal
data were recorded in standardized forms. Prenatal routine maternal
testing was done for toxoplasmosis, hepatitis B and C, human
immunodeficiency virus (HIV), and syphilis. Gestational age was
determined in completed weeks by obstetrical
estimation18. Spontaneous abortions and stillbirths
were defined as embryo or fetal losses that occurred before and after 20
completed weeks of pregnancy, respectively.
Newborn data were extracted from medical records. Birth weight and head
circumference measured before hospital discharge were classified
according to the INTERGROWTH-21stcriterion19 as recommended by the PAHO. Microcephaly
was defined as a head circumference (HC)>2z scores below
the appropriate mean for a given age, sex, and gestational age, and
severe microcephaly was defined as an HC>3z scores below
these standards19,20. All infants were initially
classified according to the presence of microcephaly, neonatal
neurologic dysfunctions, and other birth defects coded as major or
minor21.
Combined neonatal abnormalities detected in fetuses/infants were defined
as potentially related to congenital ZIKV infection both according to
Honein et al.6 and Pomar et al.1criteria as mild/moderate or severe complications compatible with CZS.
Typical CZS phenotype was defined as those classified by the former
authors as “brain abnormalities with or without microcephaly” and by
the latter as those presenting “severe complications compatible with
CZS or fetal loss”. We did not to exclude the first-trimester
spontaneous abortions from the adverse outcomes but excluded the
fetuses/newborns with other known causes for the CNS anomalies from the
typical CZS phenotype definition. Both decisions were taken to allow a
better understanding of the complete investigation of cases.
Additional assessments were planned for all infants with microcephaly
and other major neurologic findings and those who were born or referred
within 3 months of life as follows: Hammersmith Neonatal Neurological
Examination (HNNE)22; pediatric evaluations at 3-6
weeks and 3+ 1 months focusing on clinical and neurological
findings and the developmental milestones; Bayley-III scale of infant
and toddler development screening test23 performed by
a certified examiner; hearing screening using both Transient Otoacoustic
Emissions (TOAE) and automated auditory brainstem evoked responses
(AABR-35dBHL); cranial ultrasonography and/or other neuroimaging studies
performed by an experienced physician and reviewed by two
board-certified radiologists; complete eye examination including
indirect ophthalmoscopy by ophthalmologist.
The HNNE optimality compound score is calculated for each of six
categories (tone, tone patterns, reflexes, movements, deviant signs,
behavior) of a neurological evaluation containing 34 items. Scores
between 30.5 and 34 are found in more than 95% of low risk term
infants22. For the purpose of this analysis, an
optimality score <30.5 at birth were considered suboptimal.
For infants with no HNNE complete evaluation, a short neurological exam
proforma of this test with 13 categories was applied24and the presence of any abnormal sign was considered suboptimal.
Regarding the Bayley screening test, infants were tested according to
the application guidelines in five domains: cognitive, communication
(receptive and expressive), and motor (fine and gross). Scores were
classified as competent or emerging/at risk in each
domain23. An infant with at least two of the
neurologic/neurodevelopmental evaluations categorized as suboptimal,
abnormal, emerging or at risk was classified with a possibleneurologic abnormality.