I am reading thru the guidelines for GBS treatment in Canada. If a mama is + she gets antibiotics when water breaks or at the start of labor. If mama's status isn't known, it is recommended to give abx if water is broken for 18 hours, maternal fever, or labor starts before 37 weeks. What I don't understand is why there is a difference? Why are there certain criteria for unknown, but standard abx for + even if none of the "risk" factors (fever etc...) are involved?