Canadian researchers from the University of Alberta analysed a body of published research into approaches to potty training.
One Canadian study of 4,332 children in 2006 found a higher incidence of incontinence and urinary tract infections among children who were potty trained later than 18-months-old. Their findings also indicated that children who had been rewarded and punished during toilet training were more likely to have had symptoms of incontinence or infections, whereas children encouraged by their parents experienced no symptoms.
Another piece of research by the University of Bristol found that potty training children after two-years-old was associated with a higher risk of daytime wetting.
The American Academy of Paediatrics and the Canadian Paediatric Society advises parents start potty training their children at 18 months of age and suggests that the child must be interested in the process.
The authors of the study claim that over the last century the current child-centred approach has resulted in children being potty trained at an older age than before.
Dr Darcie Kiddoo from the Division of Paediatric Surgery and Urology at the University of Alberta in Canada, who led the study, said, ‘Toilet training is felt to be a natural process that occurs with development, yet very little scientific information is available for physicians who care for children.
In reality, toilet training is a complex process that can be affected by anatomic, physiologic and behavioural conditions.'
The study Toilet training children: when to start and how to train is published in the Canadian Medical Association Journal.