Longitudinal study of bowel and bladder control by day and at night in the first six years of life. I: Epidemiology and interrelations between bowel and bladder control.

The development of bowel and bladder control by day and at night during the first six years of life in 320 Swiss children in the Zurich longitudinal study (1955--1976) is described in detail. A scoring system was used which included intermediate stages of control. With toilet-training started in 96 per cent of the children during the first year of life, bowel control was completed in 32 per cent at age one, in 75 per cent at age two and in 97 per cent at age three. Complete bladder control by day and at night were established in none of the children at age one, in 20 per cent at ages two and three and in 90 per cent at age four. Complete bowel control and complete bladder control by day and at night were found in 5 per cent at age two, in 11 per cent at age three, in 77 per cent at age four and in 91 per cent at age six. The significant relationships between bowel control, bladder control during the day and bladder control at night (p less than 0-001) demonstrate that the same developmental process acts in bowel and bladder control. Highly correlated to each other, first bowel control develops, then bladder control by day and finally bladder control at night. The relevance of these interrelations for toilet-training and for the management of enuretic and encopretic children is discussed.