Objective: This study investigates the association between age at initiation of toilet training and development of daytime bladder control. The main aim is to examine whether initiation of toilet training after 24 months is associated with increased odds of daytime wetting in school-age children.
Method: The study is based on more than 8000 children, aged 4.5 to 9 years, from a UK birth cohort--The Avon Longitudinal Study of Parents and Children. Using multinomial logistic regression, the analysis examined the association between age at initiation of toilet training and 4 previously established trajectory groups representing different patterns of development of daytime bladder control (described as "normative development," "delayed acquisition," "persistent daytime wetting," and "relapse").
Results: Compared with children whose toilet training was initiated between 15 and 24 months, initiation of toilet training after 24 months was associated with higher odds of membership to the trajectory groups representing persistent daytime wetting (1.52 [1.23-1.88], p < .001), delayed acquisition of daytime bladder control (1.47 [1.29-1.66], p < .001), or relapse in daytime wetting (1.52 [1.28-1.80], p < .001). Adjustment for confounding variables, including sex, developmental delay, difficult temperament, and the mother's self-reported depression, did not alter the main conclusions.
Conclusion: There is evidence that initiating toilet training after 24 months is associated with problems attaining and maintaining bladder control. It is possible that delaying the onset of toilet training until after 2 years prolongs the exposure time to potential stressors that could interfere with the acquisition of bladder control, resulting in delays in achieving continence and susceptibility to relapses in daytime wetting.