In this equivocal time of mothers working outside the home -- sometimes with painful ambivalence -- Dr. Burton White, director of the Massachusetts-based Center for Parent Education, has taken a strong stand:

He is against full-time substitute child care for children from birth to age 3.

There are more than a few people who don't like White's position -- stressed in his latest book, "A Parent's Guide to the First Three Years" (Prentice Hall, $10.95) -- and have told him so. Vehemently.

Why all the fuss?

"I'm hitting guilt," says White, "and to me [guilt] is the most destructive human emotion. I don't tell mothers to stay home, but someone has to talk to the impact [of substitute child care] on the child . . . and you can't eliminate anxiety responsibly.I am telling parents what's going on [with the child] and it's still their choice as to what to do."

White realizes many women have to work full time in order to help or fully support their families. But for those women "fortunate enough to have a choice," he maintains "the majority of a baby's waking hours should be spent with parents or grandparents."

In his book he declares himself a "strong advocate of substitute child care on a part-time basis for all families who would like it."

"Time off is important," says White, 51, who has four children, "for the parent's psychological relief whether through outside work or relaxation."

Though White's message may take some of the pressure off women who want to stay home with their children, it hits hard women struggling with career, young children and the unavailability of part-time work.

White, who has been criticized for his arbitrariness, refuses to be like "other professionals who tell parents what they want to hear.

"Actually, he says, "I'm finding that the bulk [of readers who write to him] seem to sigh a sigh of relief that someone of authority has taken a stand."

That authority -- or why his words are apt to be taken as seriously as Spock's descriptions of chicken pox -- is based on White's 20 years of researching the "critical first three years of life." From 1965 to 1978 he directed Harvard's Pre-School Project, where he took active part in the investigation of infant-toddlers' early development, education, and interaction with mother, father and siblings.

As a developmental and educational psychologist, highly respected in his field, White's focus is mainly on the learning and practical needs of the infant-toddler.

In his new book (and its 1974 paperback companion issue, "The First Three Years"), growth is divided into seven phases of development. He spells out exactly the kinds of growth, curiosity, play and exploration to expect and encourage.

The difference between White's observations and other "clinical" growth charts is his sensitivity to the care and excitement of parents with each step. c

It is precisely the sharing of these big and small accomplishments -- the disappointments -- that he feels essential in a child's full development. Few nursemaids or day-care centers, he believes, can provide this interchange -- even if they wanted to.

White concedes, however, the difficulty of those very demands -- "for which parents were in no way prepared or supported."

The answer, writes White, is training and educating parents in children's developmental needs.

"I think of a child's development and this problem [lack of government-supported early-education programs for parents] as an 18-story building -- we pay to do the top 12 to 18 stories, we pay the most prestigious mason to do the 6 to 10 floors, but we'll take anyone who's walking on the street to build the first five stories, the foundation."

White's extensive work with infants and toddlers has shown that by age 3 many children fall behind in the development of basic abilities (language, motor skills, etc.) and that poor development "seemed, on the basis of many reports, to be very difficult to reverse."

If you look at a group of first-graders who are not doing well, says White, "They didn't look good at 3 or 2, but they all looked good at one year of age. Any falling behind happens at the end of the second year of life."

White in 1978 established his center, a nonprofit public-service organization that encourages support of educational programs for parents and offers assistance to professionals concerned with children, emphasizing the first three years.

The staff reviews virtually everything on children -- from a major research project on infant bonding to the latest "Jack-in-the-box" toy -- and the information is disseminated through its newsletter.

"The response to both the professional and parent programs is encouraging," says White. "We have heard that parent-support programs have started all over the country.