In 1995, Danish researchers announced they had found a site on human chromosome 13 that is responsible, at least in part, for nighttime wetting. If both parents were bed wetters, a child has an 80 percent chance of being a bed wetter also. Experts believe that other, undetermined genes also may be involved in incontinence. Structural Problems Finally, a small number of cases of incontinence are caused by physical problems in the urinary system in children. Rarely, a blocked bladder or urethra may cause the bladder to overfill and leak.
Nerve damage associated with the birth defect spina bifida can cause incontinence.
In these cases, the incontinence can appear as a constant dribbling of urine. Daytime incontinence that is not associated with urinary infection or anatomic abnormalities is less common than nighttime incontinence and tends to disappear much earlier than the nighttime versions. One possible cause of daytime incontinence is an overactive bladder. Many children with daytime incontinence have abnormal voiding habits, the most common being infrequent voiding. If the bladder contracts strongly and without warning, the muscles surrounding the urethra may not be able to keep urine from passing.