I wonder whether there is a window during pregnancy for a Zika infection causing microcephaly.  eg, thalidomide caused different defects depending on which day of the pregnancy the mother took it -- take it on the Nth day and you get blindness, on the Mth day you get malformed limbs.<p>If it&#x27;s something like &quot;only a risk during the second trimester&quot;, then that 28% chance becomes &quot;100% during second trimester&quot;.