BOSTON--The merger of Brigham and Women's Hospital and Massachusetts General Hospital (MGH), Harvard's largest teaching hospitals, will shift the medical centers' focus more to primary care networks with an eye to incorporating the Medical School's other teaching hospitals, officials said at a press conference yesterday.

It is unclear at this point what the effects the merger will have on staff, on competition among Boston's numerous hospitals and on the services the two hospitals would provide or share.

"It promises to be an interesting and challenging evolutionary process which will not happen overnight and will be [beset] with extraordinary problems and sensitivities but will be very rewarding," said J. Robert Buchanan, general director of MGH.

Business School dean John H. McArthur, chair of the board of Brigham and Women's, played a key role in the merger. McArthur and other officials would not say how many--if any--of the more than 18,000 employees at both hospitals would be laid off as a result of the merger.

"We may end up with more than we have now," McArthur said. "But I believe we will have to have a [large] education and retraining program."

Medical School Dean Daniel C. Tosteson '44 said yesterday he had known about the planned merger for several months. Reports anticipating yesterday's press conference surfaced Tuesday.

"The decision of Brigham and Women's to make it two-fold came about in June," he said. "I applaud the vision and courage of the leadership of Brigham and Women's and MGH in coming together."

Tosteson said he considers the merger part of a larger process of eventually unifying the entire Harvard medical faculty. He had announced this summer that Harvard's five flagship teaching hospitals--Brigham and Women's, MGH, Beth Israel, Children's and Deaconess--would be participating in greater cooperation with the goal of eventual unification.

The medical school dean also said yesterday he considers the merger the first step in the eventual consolidation of the major teaching hospitals.

"It's rare to have five compounds react together simultaneously. Usually when five react it starts with two," he said. "It's not surprising to me that it's more comfortable for some institutions to go about it this way."

The presidents of Beth Israel and Children's told The Boston Globe they had not been informed of the details of the arrangement. McArthur said, however, that he plans to spend the next few days talking to various people atthe three hospitals about the merger.

Tosteson said he did not believe officials atthe other three hospitals were unhappy over theagreement. "I would say there is high interest,"he said. "I think they recognize the logic behindit."

McArthur, who was touted as "the prime moverbehind the negotiations" in a Globe articleyesterday, refused to describe himself as theprimary catalyst, but said he had been veryinvolved in planning the agreement.

"It's very difficult for that large a group toaddress the extent of change in front of us," hesaid. "Our feeling with each hospital was that ifthe larger idea was going to work these two wouldhave to be involved in it."

Jack Connors, a trustee at Brigham and Women'swho directed the press conference, said the mergerwas a "historic occasion."

"[McArthur] deserves more than partial credit,"Connors said. "[But] I would say it would not beappropriate at all to say that he was the fatherof this agreement."

The merger was finalized at a meeting thisweekend, attended by McArthur, other officials ofboth hospitals, and lawyers from the Boston firmRopes and Gray.

McArthur said the merger was presented to thegroup as a case study incorporating costs andresources at both hospitals. "We tried tounderstand in Boston and then in Massachusetts therelative strengths of each of these hospitals," hesaid.

The trend in health care reform toward primarycare was a major factor in the decision to merge,official said.

"We consider this an important step for helpingus deal with a rapidly changing health careenvironment said Robert J. Boyd, chair of the MGHPhysicians Corporation. "We are particularlyconcerned with maintaining our high standards ofpatient care."

Eugene Braunwald, chair of the Brigham andWomen's department of medicine, said the combinedhospitals will have a greater emphasis of primarycare, a stated priority of the Clinton health careplan. "We hope to develop...a network which willtilt the balance of care to primary care andcommunity service," he said