Rather than settle once and for all the bitter national debate over the public funding of abortions for the poor, the U.S. Supreme Court's rulings last week and uesterday appear to have simply enlarged the battle ground and further complicated the issue.

Not only must the legislatures of the 50 states now decide if they want to end elective Medicaid abortions, they must also face the difficult task of deciding exactly what makes an abortion medically necessary, rather than elective, a question that the Supreme Court left open.

While all states now pay for "therapeutic" - or medically necessary - abortions, the definition of therapeutic varies from state to state.

Some states had defined therapeutic abortions as those that were a "medical necessity" (without defining that), while others provided Medicaid funds only for abortions necessary to save the life of the mother.

The first question facing the states is what they intend to do it HEW ends federal reimbursement for abortions that are not medically necessary, HEW's actions now hinge on whether a lower court judge upholds a ban on using federal funds for abortions.

State health officials in Maryland, where $1 million was spent last year to provide abortions to 5,000 poor women, say they will continue to pay for such procedures out of state funds - unless the legislative forbids them to do so.

In Virginia, however, Dr. R. C. Ray of the state Department of Health said that if federal funding is ended, free abortions will be ended. "We don't have that kind of funds," said Ray, referring to the $395,000 in federal money that paid 90 per cent of the bill for the 5,100 Medicaid abortions there last year.

District officials, however, are not sure what they're going to do. As late as Tuesday, Department of Human Resources Director Albert P. Russo said "it's a decision I prefer not to make until it's absolutely necessary." Russo said that he would consult with Mayor Walter Washington and formulate a policy within one week of the Supreme Court's ruling.

At the present time, almost one third - 300,000 - of the 1.1 million abortions performed in the United States each year are paid for by Medicaid.

While the proportion of state and federal dollars varies from state to state, any cuttoff of federal funding will leave the states with a mammoth share of the bill for Medicaid abortions, which was $50 million last year.

In some states such as Connecticut, Virginia and the District, the federal government pays 90 per cent of the Medicaid bill.

By holding last week that public funding of abortions is a legislative matter, and then ruling yesterday that a U.S. District Court in New York must rehear the arguments over last year's congressional cutoff of such funding, the U.S. Supreme Court once again made the definition of "medical nexessity" the abortion battle ground.

Prochoice forces, who believe that women should be also to choose whether to have an abortion, now feel that their only hope of having Medicaid payments for abortions continue is to have the courts broadly define "medical necessity," which the antia-bortion forces would limit to saving the life of the mother.

Alfred Moran, vice president of Planned Parenthood of New York City, one of the groups that sought the original injunction against the implementation of the so-called Hyde Amendment, last year's congressional cutoff of abortion funds, argued yesterday that Hyde is still unconstitutional because it is too restrictive.

Moran and other prochoice attorneys are interpreting the Supreme Court ruling to include "medically necessary" abortions. The Hyde Amendment allows abortions only to save the life of the mother.

The battle over the definition of medical necessity signals a possible return to less liberal days when women were forced to use such subterfuge as pro forma letters of necessity from psychiatrists.

In 1968 when the Commission Professional and Hospital Activities did a survey of hospitals performing therapeutic abortions, it found that 70 per cent of the 4,625 abortions performed that year were done for psychiatric reasons, compared to 23 per cent four years earlier, when abortions were less acceptable.

The rulings of the past week have shattered whatever vague uniformity of policy regarding medicaid abortions there was among the states.

Before last week's decision, only six states not provide funding for Medicaid abortions. Nine other states had similar laws or regulations limiting Medicaid abortions, but had been under court orders to provide the operations until the Supreme Court ruled last week.

There is now considerable confusion in those nine states as to which abortions should, and should not, be' paid for.

North Dakota ceased providing Medicaid abortions last week for any purpose other than to save the mother's life.

In Connecticut, women must now obtain a doctor's certification of medical necessity before obtaining a publically financed abortion.

In New York, one of the first states to enact a liberal abortion law, health officials are continuing to pay for all abortions contending they are all medical necessities. This week Gov. Hugh Carey, a Catholic, said that although he is personally opposed to all abortion, he feels the state would discriminate against the poor if it failed to do otherwise. Medicaid financed 35 per cent of New York's 134,500 abortions last year.

Last year, the New Jersey legislature passed a law preventing the state from paying for any abortions other than those necessary to save the mother's life.

A court injunction prevented that law from ever taking effect, and now New Jersey officials say they will pay for all abortions under Medicaid until they notify welfare recipients to the contrary with notes in their August welfare check envelopes.

John J. Kent, assistant secretary fro health in Maryland, explained his department's decicion to finance Medicaid abortions out or state funds by saying, "we do not want to put the lives of women in jeopardy who have decided to have an abortion simply because of a lace of federal funding."

While the argument is made by the prochoice forces that an end to Medicaid abortions would force poor women to either have unwanted children or risk their lives or health at the hands of back alley abortionists, there is no way to determine how many of these 300.000 women will instead be able to find a way to pay the $150 for an abortion themselves.