Leaders of a Maryland antiabortion group said yesterday they have collected more than 50,000 signatures on petitions seeking a statewide referendum designed to restrict the use of state Medicaid funds to pay for poor women's abortions.

However, the group still must clear a legal hurdle before this volatile issue can appear on the November ballot. A Montgomery County Circuit Court judge is expected to rule today on whether the current state guidelines governing the use of abortion funds are a proper subject for a referendum.

The antiabortion group, Stop Taxes for Abortion, would like the voters to approve a measure that would allow the state to pay for abortions only when the mother's life was in danger.

The guidelines set forth in the state budget passed in April, however, are considerably broader. One guideline allows Medicaid abortions if one doctor certifies that the mother's health would be harmed by a continued pregnancy. The definition of "health" - physical, emotional, or mental - is left up to the doctor.

Maryland Attorney General Francis B. (Bill) Burch has asserted that under the state Constitution, since the guidlines are included in the state budget, they are not subject to a voter referendum.

Last May, a few weeks after the much-debated guidelines were passed as a condition for spending certain funds in the state budget, the group began its petition drive. Members were required to obtain signatures from nearly 29,000 registered Maryland voters - 3 percent of those voting in the last gubernatorial election - by June 30.

George Yourishin, the group's executive director, said the members have surpassed that goal, collecting nearly 25,000 signatures in Montgomery and Prince George's counties and another 25,000 in the rest of the state.

But their efforts were dealt what appeared to be a fatal blow last May 31, when the attorney general asserted, that the guidelines were not subject to referendum.

Maryland Secretary of State Fred Wineland has since refused to accept the group's petitions for certification. Such certification is an essential first step for getting an issue on the ballot.

The antiabortion group is now seeking a court order to force Wineland to accept its petition and to declare that the guidelines are, in fact, a proper subject for referendum. Lawyer James Kolb argued yesterday before Judge Joseph M. Mathias that the group is seeking to bring only the "conditions" for the use of state funds to referendum, and that this is different from holding a referendum on the funds themselves. Assistant attorney general Thomas Plank argued against this contention.

Marylanders for the Right to Choose, a citizen coalition that lobbied for the more liberalized guidelines, has made no effort to combat the petition drive.

"When they started this we knew there was a constitutional prohibition against getting it on the ballot," said Ilse Darling, of the Right to Choose group. "We think their effort is kind of hopeless."

Though Stop Taxes for Abortion has no official backing from the Catholic church in the state, many of the petition signatures have been collected outside individual churches, said Yourishin. The petition drive has been announced from pulpits, and signs announcing the drive have been observed in several area churches.

Both sides in the court case have indicated that if Mathias' ruling goes against them, they would likely appeal to a higher court.

The Maryland budget for fiscal year 1979 - which begins July 1 - includes about $1.6 million set aside to pay for Medicaid abortions. The budget, including the broad abortion funding guidelines, was passed after emotional debate between the majority of the House of Delegates, which sought severe restrictions, and the majority of state senators, who wanted no restrictions at all.