Studies estimate that raising a child costs anywhere from $29,700 to more than $200,000. In his recent book, Costs of Children, Washington economist Lawrence Olson puts the figure at nearly a quarter of a million dollars: $226,000 in today's dollars for a son and $247,000 for a daughter.

Olson calculated the costs of raising a child from birth through age 22 -- assuming he or she attends a private college and pays for part of the cost -- based on spending patterns of the average American family.

The average family spends 24.2 percent of their total income on boys and 26.4 percent on girls, says Olson, vice president of SAGE Associates. His work was funded by a grant from the National Institute of Child Health and Human Development. Girls cost more than boys, he says, because families spend more on girl's transportation, recreation and entertainment.

Olson, 37, says he and his wife "have not yet decided whether or not to have children." Among his other findings:

* The largest share of the cost of children is spent on food consumed at home, followed by housing, education and other items, transportation, health care and clothing.

* Higher income people tend to spend higher amounts, but a smaller percent of their income, on their children.

* Children raised in the South cost more than those raised in the North.

* Families with more education spend more on their children.

* The younger the parents, the more they are likely to spend on their children.

* Expenses are relatively high in the year of birth, fall until age 5 then begin a rise that continues through the child's entire period of dependence -- with greatest costs during college years.

* Children are cheaper to rear when there are more than one.

"If you took the money you would spend on a first-born son," Olson says, "and instead put it in the bank, by the time the kid would turn 23 you'd have $335,000 in 1982 dollars. At this point, when the couple would be perhaps 45 years old, they could retire on this nest egg. Putting these savings in a money-market fund at 12 percent interest could provide a yearly income of $40,200."