Sequential acquisition of toilet-training skills: a descriptive study of gender and age differences in normal children.

Objective: To compare the ages, by gender, at which normally developing children acquire individual toilet-training skills and to describe the typical sequence by which children achieve complete toileting success.

Methods: A longitudinal survey was conducted of a cohort of children who were 15 to 42 months of age and attending 4 pediatric practices in the Milwaukee area (2 inner city and 2 suburban) from 1995 through 1997. Parents completed background surveys, and each child's development was assessed using the Bayley Scales of Infant Development II. Each week for 12 to 16 months, parents completed a training status survey (TSS). The TSS, designed for this project, included information on daily toilet-training status (eg, number of urine successes on a 5-point scale) and 28 weekly toilet-training behaviors rated on a 5-point Likert scale from 1 (never) to 5 (always). Children were considered to have acquired a particular skill when they received a rating of 4 or 5 on the TSS scale. The median age and interquartile range for children for each toilet-training skill are reported for girls and boys separately using survival curve analysis. Ages at which each gender achieved these skills are compared using a log-rank test.

Results: The study included 126 girls and 141 boys; 88% were white. Parents submitted a total of 10 741 weekly surveys (range: 1--73; median: 49 per child). Girls demonstrated toilet-training skills at earlier ages than boys. The median ages for "staying dry during the day" were 32.5 months (95% confidence interval: 30.9--33.7) and 35.0 months (95% confidence interval: 33.3--36.7) for girls and boys, respectively. The median ages for readiness skills for girls and boys, respectively, were as follows: "showing an interest in using the potty," 24 and 26 months; "staying dry for 2 hours," 26 and 29 months; "indicating a need to go to the bathroom," 26 and 29 months. There was a marked concordance in the sequences in which girls and boys achieve individual skills. In addition, the interquartile ranges of the toileting skills varied from 6.9 to 11.4 months in girls and from 7.5 to 14.6 months in boys.

Conclusions: In this study population, girls achieve nearly all toilet-training skills earlier than boys, including successful completion. Most children do not master the readiness skills until after the second birthday. The range of normalcy for the attainment of individual skills may vary by as much as a year.