About 4,000 nurses at Brigham and Women’s Hospital have postponed a planned strike that was set to begin Wednesday, giving members time to vote on what Mass General Brigham calls its “best and final” contract offer. The Massachusetts Nurses Association said Saturday night that the strike would be put on hold while nurses review the proposed agreement. The union said members will decide what happens next. If they reject the offer, a strike is still possible; the hospital said the union would have to provide a new 10-day notice before a walkout. The negotiations have dragged on for months, with wages and health insurance costs among the central disagreements. The union says the hospital’s proposal would amount to a multiyear wage freeze, while the hospital says nurses continue to receive raises as they advance through the wage scale and are already among the highest-paid nurses locally and nationally. The hospital said it made concessions on several union priorities during its 27th bargaining session and presented its final proposal to reach an agreement. It said the offer recognizes nurses’ contributions while accounting for responsibilities to patients, employees and the hospital’s long-term financial strength. The nurses’ union said its bargaining committee delayed the strike to let members weigh the complex offer and consider the potential effects of a walkout on both nurses and the community. It accused the hospital of refusing cost-of-living increases and said that approach could weaken the union and put patient care at risk. In July, Brigham nurses held a one-day strike. The hospital then locked them out for four additional days under obligations related to temporary workers. The planned open-ended walkout would have been a more prolonged disruption for patients and hospital operations.