New Jersey hospitals rose from 13th to 3rd safest in the nation this spring because of their success preventing patients from falling, contracting infections and other suffering caused by avoidable mistakes, according to the newest Leapfrog Hospital Safety report card. Of the 67 general acute-care hospitals that participated in the survey, 30 earned an “A” — six more than the last round in the fall. Two hospitals improved by two grades: Robert Wood Johnson University Hospital Hamilton and Saint Michael’s Medical Center in Newark. No hospital flunked but one, CarePoint Health Christ Hospital in…