When Assistant Labor Secretary Olena Berg opened a new campaign to educate US workers on retirement saving last fall, she singled out one group with an especially tough row to hoe if they want to live comfortably after 65. Statistical trends show that women run a greater risk than men of spending their retirement without a comfortable pension benefits package - or even in poverty, Berg said.

The graying of the US workforce, rising costs and stagnant wages, plus the longer lifespans enjoyed by current generations, make saving enough for retirement a bigger challenge for everyone. But for a variety of reasons, the assistant secretary noted, women have always needed to take greater responsibility for their retirement planning.

The idea that women face greater hurdles in the working world than men is hardly news. Some three decades after the women's rights movement began - and female workers' share of the overall job pool began to take off - women still earn less than men.

But if anything, women's plight in retirement is worse, and more resistant to change.

Half of elderly women living alone had incomes of less than $9,500 per year in 1992, and 80% of the widows living in poverty were not poor before the deaths of their husbands. Women are more dependent than men on Social Security to fill out a comfortable retirement income package, which most financial experts define as 70% to 90% of pre-retirement income. According to a 1991 Social Security administration survey, the program's payments in the 1990s will provide some 59% of pre-retirement earnings to those retirees who earned 50% of average US wages. To those whose earnings were at or over the maximum Social Security taxable wage base, Social Security provided only 24%. Because women live longer, the discrepancy between what is needed for a secure retirement and what Social Security provides will become more pronounced as they age.

But the program is structured against women in other ways as well. While the Social Security law is also gender-neutral, it was designed, like traditional defined benefit plans, to meet the needs of a "traditional" family consisting of a lifelong breadwinner and a lifelong homemaker. It assumes a 40-year career, and calculates benefits based on the participant's 35 highest earning years. But the formula plugs in a zero for every year in which the participant earned nothing. Gwendolyn King, a former Social Security commissioner, says that each year counted as a zero in computing the average indexed monthly earnings (AIME) reduces an individual's monthly benefit by about $12.

Taking more than five years off from paid work means the participant begins to cut into her 35 top earning years, and so reduces the AIME on which her benefits are calculated. For women, this is more often the case than not. A 1990 Mother's Day report by the Older Women's League states that women average 11.5 years out of the workforce, compared to only 1.3 years for men. Even by the year 2030, the report notes, fewer than four in 10 women aged 62 to 69 will have worked 35 years or more in the paid labor force. The remaining 60% will have zeroes averaged into their earnings record.

Part-time work during child-rearing years can also reduce women's earnings, which translates into lower Social Security benefits.

Women's organizations have criticized the Social Security system for its treatment of working women, arguing that it was designed for the one-wage-earner, one-care-giver family model. But despite the complaints, concerns over the system's future funding problems have forestalled consideration of any fundamental changes to help women.

The end of the one-job career and the rise of defined contribution plans may help level the playing field for women and men when it comes to retirement benefits by shortening the time men spend with any one employer. But men's loss is certainly not women's gain. Current Population Survey data from 1993 shows that 26% of 401(k) plan participants making $15,000 to $19,999 per year contributed less than 5% of their annual earnings, compared to just 12.8% of those making more than $50,000.

Making matters worse, women tend to invest more conservatively than men. Berg says women are more likely than men to concentrate their 401(k) assets in fixed income securities that produce a lower rate of return over the long haul.

But like other future retirees, much will depend on women themselves, and the intelligence they bring to managing the opportunities for savings that they already have or can create. As more baby boomers - including women - move toward retirement, Berg says, they will realize the importance of retirement planning.