Mothers are coming back into literary fashion, even pushy mothers. The type therapists used to dream of as an alternative to what was called momism - the mother who focused all her efforts on herself, therefore removing all pressure from the children - has been realized, and the results were not as terrific as expected.

It is therefore interesting to look at the quintessential stage mother, the heroine of "Gyspsy," at Wolf Trap this week nearly 20 years after the show became a hit.

It's still a great show - book by Arthur Laurents, music by Jule Styne, lyrics by Stephen Sondheim and choreography by Jerome Robbins. Angela Lansbury has been in many productions, and her acting has a great gusty appeal, although she does not electrify the songs, first done by Ethel Merman.

But a strange thing has happened to the role. Most of the show is about a vibrant, brash woman full of life and love - but there's bitter twist at the end that doesn't go with the part.

"Gypsy" is not really about Gypsy Rose Lee; it is her memoirs - based on the burlesque star's autobiography, published in 1957 - of her mother. That she owned a great deal to her mother, both emotionally and professionally, is obvious in the play. But it is also obvious that she succumbs to the cheap trick of dismissing a strong, exuberant woman as being merely selfish, her feelings for her children being only her own sublimated ambitions.

Most of the show is the delightful story of a zany mother who finds conventional life boring and carves out something more exciting for her two daughters (the other became actress June Havoc) and miscellaneous other children she picked up going another on the vaudeville circuit. Then suddently, at the end, there is a bitter outburst in which the mother is made to convict herself, with such declarations as "I was born too soon and started too late," "It wasn't for me - if it wasn't for me . . ." "I just wanted to be noticed," and then a chorus of "Me-me-me."

Becaus the songs are so good, this is theatrically effective. But it is not the character that was built up as the heroine of this show - one can practically hear the voice-over of the daughter's therapist explaining away all the lovablesness of an eccentric mother, in the approved thinking of the era.

In any case, it's still a good show, and this production, in spite of severe sound transmission problems, is not to confused with the summer-circuit star-vehicle type that used to stop at Shady Grove before that went out of business.