Although a recent report showed that one in five taxpayers eligible for the the Earned Income Tax Credit (EITC) will fail to claim it, researchers from the University of California, Davis say that expectant mothers may not want to miss out.The tax break, instituted in 1975 to help families of low and moderate wage earners offset the burden of Social Security taxes, added $2,200 to the average filer's return, according to TIME magazine who looked at why the credit is so often overlooked.