The high court, in a 7-2 ruling issued Monday, overturned a lower-court decision that said decades-old maternity leaves should count in determining pensions.

The court's decision "forces women to pay a high price today because their employers discriminated yesterday," said Debra L. Ness, president of the National Partnership for Women and Families.

Four AT&T Corp. employees who took maternity leave between 1968 and 1976 sued the company to get their leave time credited toward their pensions. Their pregnancies occurred before the 1979 Pregnancy Discrimination Act, which barred companies from treating pregnancy leaves differently from other disability leaves.

AT&T lawyers said their pension plan was legal when the women took pregnancy leave, so they shouldn't have to recalculate their retirement benefits now. Congress did not make the Pregnancy Discrimination Act retroactive, they said, so the women should not get any extra money.