Nocturnal enuresis, also referred to as primary nocturnal enuresis, is the medical term for bedwetting.
Nocturnal enuresis applies specifically to children who have always wet the bed, as opposed to the other forms of bedwetting, including secondary enuresis (which is when a child has been dry for a consecutive period of six months and then starts wetting the bed again).
Bedwetting is an extremely common. In fact, up to 15% of five year olds and up to 5% of ten year olds wet the bed. Around 97% of children have grown out of bedwetting by the age of 12, so most cases are nothing to worry about and simply require some love and support.
The cause of bedwetting for a child who has always wet the bed is usually fairly common bladder development delays, amongst other causes, which generally iron themselves out over time.