At Barnes Hospital in St. Louis indigent pregnant women are required to put up $250 before they will be admitted for delivery, and doctors on the staff have been ordered to limit Medicaid admissions to 4 percent of their patients.

At Cook County Hospital in Chicago the number of transfers from private hospitals has increased from about 125 to roughly 400 a month since federal and state cuts in Medicaid were imposed. Hospital officials say many of those transfer patients are more seriously ill than in the past.

In Houston, where unemployed workers from out of state are straining the social services network, officials at public Ben Taub Hospital say an increasing number of indigent mothers are coming to their hospital for deliveries without adequate prenatal care, while some private hospitals require a $700 to $1,000 advance from such patients.

Federal and state Medicaid cuts and high unemployment have combined to put a potentially wrenching burden on urban hospitals across the country, particularly the public hospitals that often are the provider of last resort for America's poor.

Administrators of these hospitals report an increase in the number of their patients who have been turned away from private hospitals and a rise in the number of patients not covered by Medicaid or private health insurance.

In addition, a growing number of patients have been deferring medical care, and as a consequence when they arrive at the hospital they are sicker and costlier to treat. "We are hit harder by any single cut, since 20 percent of our budget is Medicaid," James Mongan, executive director of the Truman Medical Center in Kansas City and a member of the White House staff under President Carter, said this week, speaking for many of his fellow public hospital administrators.

"What puts us in a double bind is that not only are we the most affected by the cuts, we're overburdened as the economy declines," he added.

At Truman Medical Center, for example, the number of patient days increased 13 percent between May, 1981, and May, 1982, while at the city's private hospitals it rose by just 0.3 percent.

The cuts in Medicaid and the continuing recession may lead to two important changes, both of which may be in their initial stages, in the way the nation provides health care for the poor.

The first is to shift the fiscal burden from federal and state governments to city or county governments, which already provide the largest single share of public hospital revenues.

Many cities and counties, especially in the Northeast and Midwest, already are strapped for money and may not be able to offset the federal and state cuts, particularly if there are further cuts in future years.

Even administrators whose hospitals have been able to absorb the current round of budget cuts say they fear the longer implications of such a shift.

"This place will not close," Mongan said of his institution, which cut 80 jobs last year to hold down costs. "But it will be a less capable institution unless we are able to get back some of the cuts from the city and county."

The second change is to reverse the trend that began with the inception of Medicaid and Medicare and moved health care for the poor from public hospitals to private institutions.

Some hospital administrators say they believe the country is in the beginning stages of a shift back to public hospitals as the dominant provider of health care to the poor because many private hospitals are turning Medicaid patients away.

Ray G. Newman, chief operating officer at Parkland Memorial Hospital in Dallas, warned a House subcommittee earlier this year that continued reductions in federal "social safety-net programs" could make his hospital "a dumping ground for all Medicaid patients . . . ."

"It's going to return the public hospital to the patterns of pre-Great Society," said Elliott C. Roberts of Cook County Hospital in Chicago.

San Francisco General Hospital recently saw its Medicaid and charity patient load increase 18 percent while the city's private hospitals noted an 11 percent decrease, according to a white paper prepared by the National Association of Public Hospitals.

In St. Louis, the actions taken by Barnes Hospital have increased the burden on the city's public hospital.

"Our patient load has increased, and most of it is in the 'no-pay' category," said A.W. Steinman, hospital fiscal administrator for the city, adding that it came at a time "when the city can least afford it. It's a real dilemma for the city government. We cannot turn them away."

Barnes Hospital spokesman Daisy Shepare said the changes there were instituted to help cut losses incurred by providing care to Medicaid patients.

"We are not a tax-supported hospital," she said. "There are other places for them to go."

She said the hospital loses $81 a day on Missouri Medicaid patients and $103 per day on Medicaid patients from neighboring Illinois.

Taken together, the changes now affecting Medicaid funding and urban public hospitals raise anew the question of whether poor people in the United States will be relegated to second-class health care.

Government and hospital officials say they are trying to prevent that by providing special assistance to the public hospitals, but acknowledge that the danger exists as federal and state support for Medicaid is reduced, in part because some public hospitals have older facilities and less-modern equipment.

"We don't feel we are relegating patients to a second level of care, so long as we have good quality assurance built into our system," said Barrett Toan, director of Missouri's Department of Human Resources, which was forced to institute sweeping changes in the state Medicaid program to stem a 42 percent increase in costs in 1980.

Missouri also is instituting prepaid health care programs at public hospitals in St. Louis and Kansas City as a way to cut costs and assure those hospitals of some additional revenue.

It was spiraling costs like those in Missouri that has brought stringent new restrictions at both the federal and state levels.

This year, Medicaid will cost the federal government nearly $20 billion. Medicaid took the brunt of the federal budget cuts in health for fiscal year 1982.

Congress reduced the projected cost of the Medicaid program by $932 million, with $327 million to $347 million of that directly affecting hospitals, according to the American Hospital Association.

At the same time, many states have taken advantage of new powers that were included in last year's Omnibus Reconciliation Act to institute sweeping changes in Medicaid.

A new survey by the Intergovernmental Health Policy Project in Washington shows that about 30 states have acted to cut services, eligibility or reimbursement to hospitals, doctors and clinics.

At the same time, 16 states have added or reinstated services that had been eliminated previously, according to Richard E. Merritt, the program's director.

Merritt said, however, there is no pattern to the reinstatements to suggest that states are reversing the retrenchment that began last year. Instead, it is likely to grow more severe.

To date the effects of last year's cuts have been felt unevenly around the country, with the greatest impact in areas experiencing high unemployment, state budget deficits or both.

For example, Charity Hospital officials in New Orleans said the cuts have had little effect because the state legislature picked up the slack.

In Colorado, Gary Torber, director of the Department of Social Services, said he expected no adverse effect on medical care as a result of the cuts.

"It might eliminate some unnecessary services," he said.

But other public hospital officials talk in gloomy terms about the long-term impact of the changes that are taking effect.

"There isn't any question that there's an adverse health impact, and it has come rather quickly," said David M. Kinzer, president of the Massachusetts Hospital Association. "It is putting a strain on a very, very fragile system."

The cuts also are putting a strain on patients. "Whether due to Medicaid cuts or the economy, people are appearing for delivery of babies without adequate prenatal care," said Dick Durbin, chief administrator of the Harris County Hospital District in Houston.

At Cook County Hospital, where transfer patients are more ill than in the past, more persons who show up for outpatient services are being hospitalized quickly because they have not sought treatment earlier.

"It's deferred maintenance, on a human scale," said hospital spokesman Ron Wise.