It Takes Real Money to Raise a Child
For the United States as a whole, child-rearing expense estimates ranged between $9,030 and $10,140 for a child in a middle-income two-child, married-couple family, according to the 2002 USDA annual report "Expenditures on Children by Families."
Child care costs for infants and toddlers under age 2 were the second highest child-rearing expense for all income levels, after housing. For every age category, the widest disparities in spending levels among income-groups were for child care and education expenses, with high-income families spending two to three times more than low-income families. High-income families, for example, spent almost 2.5 times as much on child care for 0-2 year-olds ($2090) as low-income families ($840). High-income families spent twice as much as middle-income families, and four times as much as low-income families, on educational expenses for their 15 to 17-year-olds.
http://www.usda.gov/cnpp/using2.htm