Urination during the first three years of life

Urination was studied in 15 normal infants and young children on 150 occasions in the course of metabolic balance studies. With increasing age, mean urine volume increased if expressed as ml/day and decreased if expressed as ml/kg/day. Urine volume was correlated with volume of intake (r = 0.697) and accounted for a similar percentage of volume of intake irrespective of age. The mean number of voidings decreased from 20.1 per day during the first month of life to 10.8 per day in the third year of life. Absolute voiding size increased with age but did not change per unit of body weight. This study establishes urine volume, voiding frequency and voiding size of normal children during the first 3 years of life.