Jackson Health System's board approved a plan Monday to open trauma units at Jackson North and Jackson South in an attempt to get ahead of a possible new competition. For 14 years, Jackson had the only adult trauma unit in Miami-Dade County, but recently the state changed its regulations to allow up to six trauma centers in the county. Kendall Regional Medical Center opened a center in November, two other hospitals are in the initial stages of opening units and the Legislature is now considering proposals to deregulate trauma completely, allowing any hospital to get into the trauma business.