Purpose: We describe the development of voiding patterns and bladder control in healthy children during the first 3 years of life.
Materials and methods: We determined voiding patterns, bladder capacity and post-void residual urine volume per 4 hours individually and noninvasively every 3 months in 36 female and 23 male healthy infants using the 4-hour voiding observation.
Results: Voiding frequency decreased slowly from 5 to 2 voiding episodes per 4 hours from ages 3 months to 3 years. We noted interrupted voiding in 33% of subjects at age 3 months but this condition was rare after age 2 years. Voiding during sleep occurred mainly during the first 7 months of life and did not continue after age 18 months. Bladder capacity increased from a median of 52 to 67, 68 and 123 ml. during years 1 to 3, respectively. As measured by post-void residual urine volume, bladder emptying was unchanged during years 1 and 2 but it decreased during year 3 (median 6 versus 0 and mean 4 versus 3 ml. per 4 hours).
Conclusions: During the first 3 years of life the number of voiding episodes, including interrupted voiding, post-void residual urine and voiding during sleep, decreased while bladder capacity increased.