As much as you would like to prevent any diaper rash on your baby, it is possible that it will occur at least once during baby’s early years.  The number one cause may very well be ammonia from urine reacting with baby’s skin and not enough changes. If you are changing every 2 hours, aim for every 1.5 hours and it will make a difference. But there are other causes for example baby is getting sick or teething.  If you have to take antibiotics and are breastfeeding than baby will get a reaction as well.