Despite what you may hear from other parents, up to 50% of children will continue to wet the bed at three years of age. Many children are much older than this before they achieve nighttime bladder control. Usually children who continue to be enuretic (bed wetters) after five years of age have a parent who was late in obtaining bladder control also.
For those children who have never achieved bladder control by the age of five years, consultation with your physician is probably warranted, as there are treatment options available to them.
Children who have been dry in the past and who develop bed wetting or even daytime wetting (enuresis) need to be examined. Urinary tract infections and emotional stress are the most common causes of this.