New-old approach to the problem of teen-age pregnancy

''It's the way we used to do things in this country.'' The words sound more like a refrain from a country-western ballad than a recipe for social reform in the 1980s. But Jewell Jackson McCabe, president of the National Coalition of 100 Black Women, is not walking backward into the future. She's describing a program for dealing with one of America's knottiest social problems: teen-age pregnancy.

She's up against some staggering statistics. There are an estimated 1 million teen-age pregnancies each year in the United States - a problem especially acute in the black community, where some researchers find that as many as 55 percent of all births are out of wedlock. But on Mrs. McCabe's side is an idea so simple that it just might work: the building of one-to-one relationships between mature, caring adults and younger people needing help.

Such relationships are as old and as natural as the extended family. Not surprisingly, however, they seem to languish wherever family ties soften, and young people, cast adrift from parental guidance, float aimlessly into maturity. Can such relationships be re-created outside the family?

The answer, based on some preliminary work with inner-city teen-agers, is a tentative but hopeful ''Yes.'' The idea even has its own name these days: ''mentoring.'' The idea of carefully structured one-on-one relationships gained currency in the 1970s in corporate circles, where it was once fashionable to think that up-and-coming female executives needed an older, and probably male, ''mentor'' to advise them and sponsor their careers. Now the term has been broadened to describe a range of relationships between successful adults willing to articulate social values and struggling youths needing an upward boost.

In a lucid statement on the goals and challenges of mentoring as a tool for social reform, Margaret E. Mahoney, president of the Commonwealth Fund (a New York-based philanthropic foundation), writes in her annual report about the waning impact of families, churches, schools, and neighborhoods on the young. As a result, she says, ''many young Americans today do not have the natural proximity to caring, mature adults or the drive to seek them out.'' Yet there remains, she continues, ''a basic human need in the young for thoughtful, loving guidance and inspiration.''

How, then, is that basic human need to be met? Enter Mrs. McCabe and her Coalition, a 5,000-member nationwide organization. Beginning in February with support from the Commonwealth Fund, the Coalition will pair 188 unwed mothers in New York and Philadelphia with as many volunteers willing to offer a steady and caring hand. For training of volunteers and matching them with teen-agers, the Coalition is relying on the expertise of local branches of the Philadelphia-based Big Brothers/Big Sisters of America. In six months, if all goes well, the program will get under way in Indi-anapolis. And if it's still on target after 18 months, says Mrs. McCabe, ''we'll replicate it'' across the nation.

In addition to the Coalition, other groups are also exploring the idea of mentoring:

* Project Redirection, funded by the Ford Foundation and the US Department of Labor, also works with pregnant teen-agers. It sets three goals for its 337 teen-agers: reenrollment in formal education, finding and holding a job, and avoiding subsequent pregnancy. Figures from an interim report on the project, though not dazzling, are significant enough to suggest that the one-on-one approach really can work.

* Over the past two summers, a six-week program sponsored by the Coalition, the Commonwealth Fund, and Hunter College in New York matched mentors with 200 minority teen-agers in supervised summer jobs - helping the young people adjust to the working world and stick with their jobs. ''I don't see (mentors) as a substitute for parents,'' says Hunter's president, Donna Shalala. But she feels the program has been very successful - because, as she says, ''it humanizes society.''

* Educational institutions are also seizing on the idea. In February, Anthony Alvarado, chancellor of the New York City public school system, will launch the Chancellor's Mentor Program to link college students and adult volunteers with as many of the city's 300,000 high school students as possible. And at Stanford University, President Donald Kennedy has inaugurated the Public Service Project to involve students both as mentors for teen-agers needing help and as proteges of adult mentors who are themselves active in volunteer work.

Worthwhile as they are, these programs barely scratch the surface. The sheer numbers of young people needing mentors is daunting. Are there volunteers enough to go around? Will they stick to the task with the necessary consistency? Can they provide firm guidance without taking on personal entanglements? Can they avoid becoming surrogate parents?

These are serious questions. But in a society groping for new structures, different institutions, and energetic ways of meeting its needs, an idea as simple as mentoring may offer a way forward. ''You don't have to be a mystic to figure out why it works,'' Mrs. McCabe concludes. ''It's a commitment to human resources and to life.''