Consumption of certain fish during pregnancy associated with poorer cognitive performance

Consumption of certain fish during pregnancy associated with poorer cognitive performance  
http://www.eurekalert.org/pub_releases/2009-11/uog-coc111209.php
 
"Children who eat fish more than 3 times per week show a worse performance in the general cognitive, executive and perceptual-manipulative areas. Those with higher levels of exposure to mercury show a generalised delay in cognitive, memory and verbal areas. Mercury is a contaminant found especially in oily fish and canned fish and to a lesser extent in white fish."