Todd and Barbara Lewis, a young married couple living in one of hundreds of new houses sprawled across Loudoun County, don't see each other much anymore.

He works days, she works nights, and they spend only one weekend day together. They talk on the phone twice a day. They write notes when the laundry needs to be washed and the food supply is low. They have 15 minutes between jobs when they are at home together, time enough to say hi and goodbye and throw in a quick word of encouragement.

The reasons for this self-imposed estrangement: a desire to have one parent at home raising their son Wright, and a need for two incomes.

"It would be lovely to be at home," said Barbara Lewis, an office assistant in a food store. "We'd have time to plant . . . flowers . . . . But nowadays you need two people in the family working or you're not going to make it."

Many parents in suburban Washington, the metropolitan area with the highest percentage of working women in the nation, are making it by adopting new, high-pressure life styles for which they have few examples to follow. Partners in two-earner households, they are older when they first become parents and are struggling to forge ahead with individual careers, maintain a high standard of living and still be what they consider model parents.

What is happening here offers a compelling picture of fundamental changes in middle-class American life styles.

The U.S. Census Bureau issued figures last month that show that the percentage of mothers returning to work in the first year after childbirth has increased significantly in the past decade, from 31 percent in 1976 to 48 percent in 1985.

And of those mothers, college graduates were twice as likely as women with less education to return to their jobs, according to the report, which found 61 percent of college-educated mothers reentering the work force.

In addition, the Joint Economic Committee of Congress, which has been tracking the economics of the baby boom generation, recently found that the mothers joining the work force at the fastest rate are those from two-parent households. This marks a change from the past, when single or divorced mothers led in these statistics.

Such data are especially relevant to life in suburban Washington, where parents tell of racing from home to work to home again. They fashion their hours to meet what few day care opportunities exist. They agree there is an increasing need for husbands to take on duties that their own fathers seldom accepted. And they sometimes wonder whether the benefits of two incomes are worth the regimen they must follow.

"I enjoy my job. I enjoy being with people . . . but my life is very stressful right now," Barbara Lewis said. "Everything is a race. During the day, it's a race with Wright. Can I get this done before he needs to be picked up? Can I get this done before he needs to be held? And then my work is the kind of job where everything needs to be done on time. I just feel like I'm coiled up ready for a race. All the time."

"The biggest phenomenon . . . is that white women are coming into the labor force," said Janice Hamilton Outtz, a research assistant for the Greater Washington Research Center. "Black women were always in the work force in Washington. But now in the suburbs, you have nearly 70 percent of all mothers working. That really dispels the vision of mother, home and a white picket fence."

Betty Adler was a divorced mother of two small children when she met Mark Rosenberg, an attorney in Washington. Adler, a college graduate with a master's degree in public health, was teaching in a day care center so she could earn a living and take care of her own children there.

The couple wed, and Adler, encouraged by Rosenberg, continued to work. Now, after four years and another child, the 34-year-old is the owner of the Kid's Place day care center in Bethesda.

The fledgling business is so demanding that Rosenberg and Adler need a housekeeper to help take care of their children, Aaron Claxton, 9, Sarah Claxton, 7, and Eli Rosenberg, 3.

"I love this business, but there are days where I think: What am I doing spending my day with other people's children?" said Adler, whose day care center accommodates 37 youngsters from ages 2 to 4.

"But then I think, I am trained to do this and I'm helping other women who need this kind of thing so that they can work," she said. "But there are still the personal disappointments. Like when I'm working hard and my little boy will call and say, 'Mommy, come home.' "

Rosenberg's life changed dramatically when he became an "instant father" at 35. But far from resisting the change, Rosenberg wanted a family in which both adults "would contribute socially, professionally and financially."

Rosenberg is the first parent to wake in the morning. He makes certain that lunch money is ready, puts the cereal on the table and starts the coffee brewing.

When he leaves for his law office, Rosenberg becomes the less flexible parent. His job is tied to appointments, meetings and situations less subject to being arranged around school plays or the unexpected emergency of a sick child.

Like many mothers who combine family and career, the brunt of the pressure falls on Adler, following her to the day care center where she arrives at 9 a.m. Working with groups of energetic toddlers, she talks to her children on the phone throughout the day. She returns home at 5 p.m. to take on the tasks of car-pooling and cooking.

When the couple meets again that day -- Rosenberg often works into the evening -- each must follow a schedule that will feed, bathe and put to sleep three energetic youngsters.

At night, as Adler is cleaning the kitchen, Rosenberg is reading bedtime stories.

"I see the stress that happens because we both work," Rosenberg said. "But not only is Betty working, but she's creating a business. That makes her a more interesting person . . . . I see it overall as a positive thing."

Adler talks with dozens of fathers and mothers every week at the day care center and hears more couples questioning how best to raise a family in a society where employers make few concessions to their personal needs, such as extended maternity leave and on-the-job day care.

Yet, she added, Washington is a city where "you're not a real person unless you have a job . . . . I think, in a sense, you can buy into that whole scene. It's like a curse.

"It used to be that mom was home and baking cookies," Adler said with a rueful smile. "Well, you don't see that anymore. People with one or two kids are saying: That's it. Not only is it financially difficult, but physically and emotionally, parents can't take any more."

As they take on the new responsibilities of child raising, these parents generally are not willing to settle for a leaner life style than they knew during their childless years. The economic crunch of the 1970s has meant less buying power for many Americans, studies by the Joint Economic Committee have shown.

Young parents interviewed for this story, who have combined annual incomes ranging from $45,000 to $90,000, said they would have to change their life styles drastically to live on one salary.

Eliminating day care costs -- which on average run about $5,000 a year for each child at a day care center -- would help stretch a single paycheck, they agree. Money for mortgages, food and clothing would be scarce. Vacations, stereos, televisions and movies would be out of the question.

"People are both responding to higher living costs here and to a standard of living that for them has become a norm," said George Grier, an owner of the Grier Partnership, an independent consulting firm that analyzes the economic markets surrounding Washington. "How you pay for it is by having everybody in the family who can work, work."

That credo has the Lewises adhering to a work schedule that some families might find incredible. They say it was the only way to meet their budget and offer the kind of family learning experience they want for their 9-month-old.

Todd Lewis, an air traffic controller assistant, works from 7 a.m. to 3 p.m. Monday through Friday. Barbara Lewis works at the food store from 5 p.m. to midnight Monday through Thursday and on Saturdays.

They live in a comfortable home, make their $800 monthly mortgage payment, and, most importantly to them, are with Wright day and night.

What their schedule does not do is leave them much time for each other.

"We have communication problems just because we spend so little time together. There's not enough time to discuss what needs to be done in the house, let alone ourselves," said Barbara Lewis, a first-time mother at age 32. "We try to make Friday evenings and Sunday special, and we try to communicate everything then. It is difficult."

Todd Lewis, 34, shies away from talking about the kinks in the family arrangement, and instead he emphasizes his belief that their new life style allows the kind of child rearing with which he is comfortable.

His mother, a teacher, quit work to stay at home with the children until they began school. Wright deserves at least what he had, Todd Lewis said.

Toward that end, the couple prepared for the time when Barbara Lewis' six weeks of maternity leave ended.

Both of their employers agreed to what they wanted: setting one schedule permanently on days and the other permanently on nights.

And now both parents know the whirlwind of working full time and raising a child full time.

"I believe that the little things make a difference," said Todd, who is the father of a 13-year-old son from a previous marriage.

"I know Wright is my responsibility and I see the things -- I see it in his eyes -- that need to be done," he said. "I wanted to have a part in orchestrating his day. And I didn't want someone else spending 40 hours a week doing that.

"I'm proud about the way we're doing this. I think we've been very lucky."