Having children often involves a sacrifice, but new numbers show just how much a sacrifice it can be, especially for mothers. According to just-released government figures:

• A two-parent household earning $36,800 to $61,900 will spend $160,140 to feed, clothe and shelter a child until age 18.

• Some observers claim that because government and employers provide poor flextime, child care and paid leave, mothers routinely become downwardly mobile in the labor market once they have children.

• A Rand Corporation study shows a woman's lifetime earnings are lowered 13 percent by having her first child, and 19 percent by having her second.

Thus, it appears that the wage gap between men and women has little to do with sex and everything to do with children. A recent study by Columbia University economist Jane Waldfogel showed how childbearing exerts enormous downward pressure on women's wages.

Using data from the National Longitudinal Surveys, Waldfogel compared the earning power of mothers and non-mothers across occupations. After controlling for age, education and experience, she found childless women now earn 90 percent of what their male counterparts earn, while mothers earn only 73 percent.

Source: Sylvia Ann Hewlett (Harvard Center for the Study of Human Values in Public Life), "Have a Child, and Experience the Wage Gap," New York Times, May 16, 2000.