Registered nurses at the Einstein Medical Center in Philadelphia ratified their first union contract on Thursday. The union, the Pennsylvania Association of Staff Nurses and Allied Professionals (PASNAP), reached a tentative agreement with the hospital on Dec. 20. In April, the nurses voted, 463 to 343, to affiliate with PASNAP. The hospital employs about 900 registered nurses.  Under the terms of the three-year contract, the hospital agreed to hire additional nurses and will work with a nurse-led committee to address staffing issues, the union said. The nurses will also gain wage increases and improved health coverage, the union said.