Peggy Polito, 20, and an associate director of MTV in New York, hid her pregnancy and morning sickness from her employer for four months, squirreling away sick days for use after the baby's birth, expected in June. There is no written company policy on maternity or child-care leave, she has been told, only sick leave and vacation leave available at her supervisor's discretion.

With her family dependent on her income and medical insurance -- her husband has multiple sclerosis and has been unemployed for two years -- Polito is about to enter motherhood on time given begrudgingly, with verbal assurance as her only job security.

Sharyn Skeeter, a Stamford, Conn., MBA, took a management job with an educational distributor only months before she learned her request to adopt an infant had been approved. She tried, and failed, to win a brief leave, then suggested she use her vacation time instead. Forget it, her boss told her: He had already hired someone in her place.

Barbara Wittig, 44, of Silver Spring, Md., didn't lose her editing job at the Army Department's Center of Military History when she adopted two Korean sisters in September. But even 17 years of government service failed to earn her support, she says, for a leave beyond the standard vacation time to get the girls settled and placed in appropriate schools.

When the older child suffered a seizure during Wittig's month off from work, Wittig blamed the pressure they were under for her to return to work. "Had I been in a situation where I was more relaxed and could have better explained what was happening to her, instead of yanking her from one place to another -- 'Come on, kid. You have to go there.' -- perhaps it wouldn't have happened."

Today, the three women have joined ranks with those calling for a uniform national standard on parental and child-care leave that the United States, alone among the world's major industrialized nations, does not enjoy. A bill now pending in the House and Senate would redress that situation by mandating a national policy of unpaid, job-protected leave for parents of newborn, adopted or seriously ill children as well as for workers with serious health conditions.

In congressional hearings, some have called the proposed standard too timid; others, too radical. But those who have suffered without one say almost any standard would be an improvement.

Says Skeeter, the Connecticut MBA who lost her job, "If there had just been some law or guidelines that the employer had to follow instead of treating me arbitrarily . . . That's what bothered me. I was treated in a very arbitrary manner. Here I had just requested a leave -- I hadn't even taken it . . . Employes deserve certain rights, not just at the whim of the employer."

Since Rep. Pat Schroeder (D-Colo.) first introduced a bill last spring -- a revised version, introduced this spring by Rep. William Clay (D-Mo.), is now under consideration in the House: its Senate counterpart was recently introduced by Sen. Christopher Dodd (D-Conn.) -- more women, and men, have come forward to testify on its behalf.

It is not just the compelling nature of their stories, however, that accounts for the growing attention being paid. It is, more than that, the sheer weight of numbers.

The past three decades have seen a virtual avalanche of women in the workplace, their growth calculated at a rate four times greater than that of men, in a massive phenomenon that has exploded traditional ideas about home and work. Fifty million women now work outside the home.

But for young women (80 percent of the female workforce is of childbearing age), job protection for pregnancy, childbirth or adoption is often minimal or nonexistent.

Current law, amended by the Pregnancy Discrimination Act of 1978, requires only that employers treat pregnancy-related health problems as well as they treat any other health condition. Most employers simply don't have disability policies, says Sheila Kamerman, professor of political science at Columbia University, who has written extensively in this area. Others may provide leaves, but only at a supervisor's discretion, with no assurance of a job upon return.

Only five states -- California, Hawaii, New Jersey, New York and Rhode Island -- have set up Temporary Disability Insurance programs providing some paid leave to women for childbirth, but not guaranteeing their jobs.

Men, too, are increasingly voicing dissatisfaction with corporate leave policy. A new study by Catalyst, a nonprofit organization focusing on career and family options, shows some of the nation's largest companies are beginning to offer leaves for new fathers. So far, however, very few men are braving conspicuous corporate disapproval to take them. Almost two-thirds of the 384 companies surveyed -- and 41 percent of those with paternity leave policies in place -- responded that "no time" was the appropriate amount of time for a man to leave work for the birth of a child.

"It's shameful," says Thomas Donahue, secretary-treasurer of the AFL-CIO, "that unlike practically every other industrialized nation, we don't have any leave time as national policy, and that . . . particularly in low-wage industries, so filled with women these days, company policies are woefully lacking . . . "

Donahue was among the witnesses speaking last month before two congressional subcommittees weighing the Parental and Medical Leave Bill. The bill would assure full-time and part-time employes up to 18 weeks of unpaid "parental" leave for the birth or adoption of a child or a child's serious illness; and up to 26 weeks of unpaid "medical" leave for a serious health condition. During either kind of leave, the employer would be required to maintain a worker's health insurance coverage and guarantee the job.

Like other proponents of the bill, Donahue used words such as "minimal" and "modest" to describe it, noting it stopped short of advocating employer-paid infant care leaves, endorsed by the Yale Bush Center in Child Development and Social Policy, composed of prominent child psychologists and social planners.

But critics view the bill differently.

"Too far-reaching for the ultimate good of the workforce and the business community," is the way Rep. Marge Roukema (R-N.J.) branded it at last month's hearing. Roukema argues for a shorter parental leave, with a prior service requirement and more restricted application to small businesses and supervisory staff.

One of the most vocal opponents is the U.S. Chamber of Commerce, which represents over 180,000 businesses -- the majority of them employing fewer than 100 workers.

Virginia Lamp, labor relations attorney for the Chamber, says reasons for the Chamber's stance include:

defbox Opposition, in principle, to any new federally mandated benefit because, she says, imposing benefits discourages the creation of more jobs. defbox Insistence that the measure would penalize small employers, even given the bill's exemption for companies of fewer than five workers.

defbox Concern about fueling a proposal for paid leave, the real bugaboo of many small employers. The Chamber has called the pending bill "the camel's nose beneath the tent."

defbox Concern that the measure could inadvertently fuel sex discrimination.

"Nonsense," retorts Kamerman. "When men were liable for the draft and when employers had to save their jobs, there wasn't a situation where employers wouldn't hire men. Women make up 45 percent of the workforce and only a very small percent of them are having babies . . . "

Nonetheless, this argument strikes a sore nerve because it suggests the kind of protectionist approach vigorously opposed by feminist and civil rights groups in this country.

Even now, in a celebrated case pending before the U.S. Supreme Court, an unlikely coalition of such groups has sided against a California woman, Lillian Garland, who lost her job after taking maternity leave, and with her employer in an attempt to strike down as discriminatory a state law requiring employers to guarantee the jobs of women who take disability leaves for childbirth. Special treatment, it is argued, works against the very persons it is meant to protect by creating disincentives to hire them.

It's exactly the kind of snare that parental leave proponents had sought to avoid by drafting the bill in a gender-neutral manner -- that is, by making child-care leave equally available to men and women -- and by extending medical leave benefits not just to new mothers recovering from childbirth but also to other workers.

"It's true," says Michele Lord, counsel for the Congressional Caucus of Women's Issues, "parental leave would probably be a lot easier to deal with on its own. The reason why it's hooked to medical leave is so that it's linked to the condition of all workers, so it's not just the lot of parents that is being improved. We don't want workers pitted against each other."

Attention, however, has focused more sharply on the parental leave portion of the bill because of awareness of the infant care problem in this country.

Says Kamerman, "Women have to deal with the problems of child care earlier in this country than in any other industrialized nation. You can see in the U.S. babies at age six weeks or two months in out-of-home child care because we don't have paid child care leave. You don't see this in other industrialized countries . . . This country spends a fortune on child development research, but when it comes to inexpensive public policy, we don't do anything about it."

To Kamerman, industry arguments against the bill are just a smoke screen. She notes the Pregnancy Discrimination Act of 1978, when proposed, caused a like panic about immoderate costs that never materialized.

"You know, if you speak to some corporate CEOs, they'll tell you this is a modest proposal and one that is really inevitable. You can't deal with a workforce that's changed the way ours has changed, with a society that's changed the way ours has changed, without making some kind of adaptation. And this is tiny."

A witness at last month's congressional hearing put it another way. Jeanne Kardos, director of employe benefits for Southern New England Telephone -- a Connecticut-based employer of some 14,000 employes -- spoke of her company's liberal benefit plan, which includes paid disability leave, 12 months unpaid maternity and paternity leave and guaranteed reemployment for up to six months.

"We have recognized," said Kardos, "that women with small children are in the workforce to stay. We want them to stay. Once you get past that hurdle, everything else is easy.

"It's clear if we force them to choose between their jobs and their children, someone's going to lose: either the company or the worker or society. It's unclear how many losers there will be . . . "