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.
Comments
Re: Authors' Response to Dr. Ravenel's Comments
Having only just seen Dr. Shum's response to my earlier comments (13 March, 2002) on his study on acquisition of toileting skills, I offer this observation. Shum appropriately points out that the purpose for their study was to add to the scientific literature concerning when children in America are finishing toilet training. One may reasonably infer that the data obtained were not intended to imply when parents should, or should be advised to, accomplish this training.
He then goes on to state that the authors "wanted to give advice about readiness skills" . . . then indicates an apparent preference for this later age of training. Although he correctly points out the absence of a controlled trial supporting earlier versus later training, neither has there been one demonstrating an advantage of the current later training compared with the earlier training described in my letter. The data cited in my letter and clinical experience strongly suggest that the earlier training is likely associated with substantially fewer problems than is later training.
It is further observed that the study was funded by a grant from Kimberly-Clark. As a manufacturer and marketer of pull-ups this might be interpreted by some as suggesting a possible bias for preferring later training and influencing the interpretations expressed by the authors.
S. DuBose Ravenel, M.D., F.A.A.P.
Conflict of Interest:
None declared
Authors' Response to Dr. Ravenel's Comments
We thank Dr. Ravenel for his thoughtful comments about toilet training. Our study has added to the scientific literature that children in America are finishing toilet training at older ages than 50 years ago. We concur with Dr. Ravenel that it doesn't make sense that children's developmental skills should have worsened. Instead, this observation reflects mostly a parental change in toilet training practices. At the conclusion of our study, our parents filled out an exit survey in which we asked them what advice they would give to prospective parents facing toilet training. Almost universally, the respondents said that parents should wait until the child is ready. Since this attitude is so prevalent among our parents, we wanted to give advice about readiness skills based on some scientific evidence rather than on anecdotes. Our study was a longitudinal observational study. To our knowledge, there has never been a controlled trial of one toilet training technique compared to another approach. Such a study would help to answer many of the questions posed by Dr. Ravenel. At the heart of the controversy in toilet training is the nature vs nurture debate. Approaches used in the 1950's do not seem as applicable for today's parents. Waiting for signs of readiness seems to fit in better with the dynamics and demands of today's families.
This study was funded by a grant from Kimberly-Clark Corporation and the research was done at the Medical College of Wisconsin.
Selection Bias?
Schum and his co-researchers provide useful information on the achievement of a developmental milestone. But because they wanted to focus on the typical sequence of skills as they were acquired, they intentionally excluded from the study 380 toddlers who had completed or were in the process of toilet training. While this approach probably does not affect the sequence of skill attainmnent, it surely inflates the ages at which distinct skills appear to be acquired.
Naturally acquired or taught skills
Schum et al present interesting data on acquisition of toileting skills. They document and comment on the increase in age at which independence at toileting has occurred. In commenting on the reasons why this has occurred, with regard to the later acquisition of skills by boys than girls,they suggest that in addition to the obvious possibility of later development of physical and language skills, another explanation may be that "parents may initiate toilet training girls at younger ages than boys."
Later in their discussion they point out that contemporary literature has maintained that toileting readiness skills typically develop between 18 and 24 months of age. They go on to "challenge this conventional wisdom," pointing out that their data show that only 2 of the 11 readiness skills were present (median) at less than 24 months of age. In their conslusions, they state, "Pediatricians should continue to emphasize the importance of readiness for the initiating of toilet training."
I would like to suggest that the prevailing emphasis on "readiness skills" is unwarranted. Sears (Stanford Univ.), Maccoby (Harvard Univ.),and Levin (Cornell Univ.) in 1957 wrote in PATTERNS OF CHILD REARING that 80% of children were completely trained for stool by their 2nd birthday. Although it is popularly assumed that earlier parent- initiated training is likely to cause toileting refusal and other problems, evidence suggests the reverse. Taubman (Pediatrics Jan, 1997) showed from their prospective study the following: (1) Among those trained for stool by age 2 years, 4% experienced toileting refusal. Those trained by age 2.5 years experienced refusal problems in 22%, with rates of toileting refusal increasing to 60% if trained by age 3 and 88% among those trained after 3.5 years.
It is illogical to believe that later acquisition of toileting skills stems from later physical maturation, when most other indices of such maturation have shown acceleration. I submit that the problem is a persistence in the belief of the importance of toileting "readiness skills" rather than expecting and encouraging parents to teach their children toileting skills at an earlier age when it can be done much more readily and with far fewer problems. "Better sooner than later"
S. DuBose Ravenel, M.D., F.A.A.P.