The wide media coverage of the possible microcephaly epidemic caused by the Zika virus (ZIKV) should lead to increased number of microcephaly cases in all Brazilian states resulting from improved notification to SINASC derived from mandatory reporting of cases of microcephaly to the Epidemiological Surveillance Service.
The current data, affected by the change of criterion determining the measurement of head circumference to suspect microcephaly do not allow to assess whether:
1. a real increase in microcephaly prevalence at birth occurred in Northeastern Brazil
2. what was the magnitude of this increase
3. was this increase due to exposure to the ZIKV or increased exposure to one or more environmental causes of microcephaly (STORCH, alcohol, prematurity, diabetes, etc