Moscow — Aina Ambrumova is a stocky, blonde contradiction in terms: a Soviet ''suicidologist.'' She wants to keep people from killing themselves in a nation where suicide, officially, just doesn't happen.
Her latest project, a 24-hour ''help line'' for victims of depression, is to begin operation in January. When the idea first came up, according to a Moscow source, one official protested: Soviet people are happy. Who needs a service to keep happy people from taking their own lives?
Talking to Western reporters, Mrs. Ambrumova comes across as a woman who knows the Soviet rules of the game, believes in her work, and smoothly manages a commitment to both.
She is not Russian, but Armenian. She believes in God. She also believes that a religious upbringing, as part of a close and warm family relationship, seems to make suicide rarer.
Yet she is a firm believer, too, in the Soviet system. And she has helped develop what she proudly labels a ''pioneering'' theoretical approach to the question of why human beings give up on life. The gist is this: Suicide in the Soviet Union, unlike in the West, does not stem from social problems. Such problems - ''unemployment, for example'' - do not exist here. Depression, Soviet style, is the exceptional, short-term response to a set of purely personal problems. Like the odd, individual conflict on the job. Or a tense marriage.
''This can happen in even the most developed of societies. . . . Take, for instance, the case of a woman who has been married for 40 years who is suddenly told by her husband, one day, that he is leaving her.''
Mrs. Ambrumova sits in a cramped office on the third floor of Moscow City Hospital No. 20. She is surrounded by the small group of psychologists, psychiatrists, and social scientists who run the ''crisis'' clinic she helped establish in 1971. She smokes American cigarettes, purchased in France.
She is ornamented smartly, even a little gaudily, by bright red nail polish and matching green neck-scarf, large earrings, brooch, and ring. In the hallway outside and the several in-patient rooms off it, a scattering of decorations welcomes the coming new year. Mrs. Ambrumova stabs at the air for emphasis. She smiles very rarely, and expounds almost nonstop on her work:
''Your telephone consultation services in the West take a more subjective approach,'' she says. ''Often, they are run by volunteers. . . . Ours will be run completely by trained staff.''
So if a young man or woman phones for help in London, the reply is apt to be: You are not alone. Human life sometimes involves problems. We all have them. I have them. I, too, have felt depressed and alone. . . . But you are not alone.
The message on Moscow's help line will be a little more clinical, Mrs. Ambrumova explains. ''We will try to find out precisely what the problem is, more objectively. And we will, for example, suggest that the caller may want to come for help.''
A few months back, the Soviet news media prematurely reported that the ''help line'' system was already in operation. Quickly, Mrs. Ambrumova and her colleagues started one such line on a limited, trial basis. ''It worked well,'' Mrs. Ambrumova says.
She stresses that applicants for help need not give their names, and that the process is ''strictly confidential.'' Most of those who phone in, she supposes, will be ''normal'' people whose depression will fit her theory of isolated frustrations in an otherwise healthy Soviet society. And at least some of the frustrated ones will end up in her crisis clinic.
When this reporter visited the center, it appeared a relaxed enough facility. Some 30 beds were divided among a series of neatly kept rooms. The doors were not locked.
Most of the patients said they had read about Mrs. Ambrumova's center in the Soviet press. Many of them were elderly. One was a young man who, in halting English, explained: ''I work in a factory near Moscow. . . . I feel better here. As to when I will leave, that depends on me and the staff.''
One patient was a 24-year-old woman who looks much younger. She runs a heavy crane for a living, and, Mrs. Ambrumova explains, ''has problems in her marriage.
''All are, or were, serious suicide possibilities. . . . But none, so far, of those who have been here has committed suicide.''
How many Soviet people, then, do commit suicide?
Pravda and Izvestia never mention the subject. The state does not release figures. ''This is correct,'' says the Soviet suicidologist evenly. ''After all, it is often difficult to distinguish what is a suicide and what is not.''