When Charles County school officials first agreed in 1978 to bus the children of some working parents to after-school baby sitters, they thought they were adopting a simple policy to fit the changing needs of the family.

Now, seven years later, the trickle of requests has swollen to more than 300 for this year alone, becoming a "logistical nightmare" and forcing school officials to rethink transport policies based on day care needs.

"Parents can no longer think of us as the final solution to their child care problems," said Chuck Wineland, an administrator who helps coordinate bus routes for 14,090 children a day.

Superintendent of Schools John Bloom said the school district's dilemma stems from has grown out of a dramatic rise in the numbers of single parents and two-career families, coupled with a chronic shortage of good day care facilities.

The number of transport requests to match day care needs has "at least doubled" since last year, said director of pupil services Bob Pendar.

Bloom said the day care requests come in "endless variations." They come from parents who are home in the morning but want their children bused to baby sitters in other locations after school; from parents who want their children dropped at relatives' houses three days a week and at baby sitters the other days, and from parents who change their child care arrangements three or four times over the school year.

"One parent was an airline stewardess who didn't know her schedule in advance and wanted to play switchy-switchy with the bus driver," Pendar said. "They set up short term arrangements that solve their problems but don't help us."

One woman who takes care of children in her home advertised in a local newspaper that she had a school bus stop right in front of her house.

"The next day, that bus had 12 or 15 extra children standing in the aisles," Wineland said. " . . . We can't run a safe, efficient bus system that way."

Wineland said a policy that was set to help parents in a bind "has opened too many doors and created massive scheduling problems in some school areas."

Present school policy calls for "one bus, one stop per child," Wineland said. The policy also says parents may transfer their child to another school nearer their day care provider only if there is room on the bus and the new school is not more than 90 percent filled.

This policy is likely to be revised in January when the school board takes it under study, but Pendar and Bloom say they do not want to close the door entirely on needy parents.

Unlike other school districts, Charles County does not have any school-based day care programs, largely because all the schools in the county's northern high-growth crescent are already overcrowded.

But Charles County is one of the few school districts in the Washington area providing any bus service to children who transfer out of their home school districts for either academic or day care reasons.

Prince George's County administrators said they have received 4,000 requests this year for school transfers because child care services were unavailable in home districts.

"All of these requests have to be verified because we are under court order to desegregate," said Barbara Traynor, coordinator of student transfers for the county. "But parents have always been responsible for transportation if their transfer request is granted."

In Montgomery and Prince George's counties, transportation is provided only to children who are attending magnet schools that have special programs designed to attract white students, a means of balancing high minority enrollments.

To respond to the day care crisis, Prince George's administrators started six "workplace" child care programs this year at schools near centers of high employment.

Traynor said the 4,000 transfer requests received this year were in addition to those made by parents who wanted to enroll their children in workplace schools.

In Charles County, teachers are also pushing for day care sites for their ranks as part of this year's contract negotiations, Bloom said.

Pendar said the school system might consider day care centers in schools as one way to relieve pressure on parents and the bus system.

"But I don't know if there's a way around the problem,' he said. "It's a reflection of the society. . . . Frankly, the nuclear family is not the one of 20 years ago."