Development of defecation in normal infants and children was analysed, based on inquiries regarding frequency and regularity of bowel movement, defecation during sleeping, call for defecation and self-control of defecation. Bowel movement was more than 2 times daily till 1 year of age, then gradually decreased in frequency, and became once everyday after 4 years of age. Defecation during sleeping disappeared after 6 months of age, and call for defecation began from 2 years of age, and all normal infants after 4 years of age called completely for defecation. Self-control of defecation was established between one year and a half and 4 years of age. The present study disclosed that clinical assessment of anal continence in postoperative infants with ano-rectal malformation and Hirschsprung's disease should be evaluated after 4 years of age, because self-control of defecation was completely established in normal infants after 4 years of ace.
