Are many four-year-olds not potty-trained before starting school?

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1. 1

   Classroom Toileting: A Collaborative Effort.

   NASN school nurse (Print) (Tourtual)Published Oct 29, 2024Checked Oct 11, 2026

   “Developmental norms suggest that children are ready for toilet training between the ages of 18 and 24 months; however, many children now enter school without this self-care skill. Many factors can contribute to delayed toilet training including child readiness, developmental disabilities, poverty, lower parental education levels, and higher rates of single and teen-aged parents who may lack parenting skills including toilet training. Most children enroll in a kindergarten program at 5 years of age. Because children will be accepted to kindergarten regardless of toilet training status, schools need to be ready for children who lack this self-care skill. Although school staff are willing to support these children, the main purpose of school is education. The school nurse can take an active role in classroom toileting programs by collaborating with school administrators, teachers, staff, and parents to promote successful toilet training and fostering a healthy learning environment.”

2. 2

   Toilet training (Wikipedia)

   WikipediaPublished Oct 10, 2026Checked Oct 11, 2026

   “Toilet training (also potty training or toilet learning) is the process of training someone, particularly an infant or toddler, to use the toilet. Attitudes toward training in recent history have fluctuated substantially, and may vary across cultures and according to demographics. Many of the contemporary approaches to toilet training favor a behaviorism and cognitive psychology-based approach. Specific recommendations on techniques vary considerably, although a range of these are generally considered effective, and specific research on their comparative effectiveness is lacking. No single approach may be universally effective, either across learners or for the same learner across time, and trainers may need to adjust their techniques according to what is most effective in their situation. Training may begin shortly after birth in some cultures. However, in much of the developed world this occurs between the age of 18 months and two years, with the majority of children fully trained by age four, although many children may still experience occasional accidents.”

3. 3

   A multicenter prospective evaluation of a decision chart for toilet training initiation.

   Translational pediatrics (Oyake et al.)Published Jul 22, 2026Checked Oct 11, 2026

   “Participants were divided into an intervention group, which utilized the TTIDC, and a control group, which followed conventional toilet training practices employed by each school. Weekly observation records were collected from July 1, 2022 to June 30, 2023. The primary endpoints were the duration of toilet training and the age at which toilet training was completed. The TTIDC was developed based on a prior pilot study.ResultsOf the 354 children enrolled, 43 completed toilet training during the study period. There was no significant correlation between the age of toilet training initiation and the duration required to complete training. However, the median age at completion was significantly younger in the intervention group (37.5 months) compared with the control group (40.8 months; P=0.002).ConclusionsThis chart may serve as an effective tool for initiating toilet training at an appropriate developmental stage. This chart may be associated with completion of toilet training at a younger age, without prematurely accelerating initiation or unnecessarily prolonging the process.”

4. 4

   Assisted Infant Toilet Training and Bladder and Bowel Health: A Global Integrative Review.

   Maternal and child health journal (Hindmarsh et al.)Published Sep 5, 2025Checked Oct 11, 2026

   “BackgroundToilet training practices vary across cultures and time. Assisted Infant Toilet Training (AITT) is commonly used in low- and middle-income countries.ObjectivesTo synthesise the literature on AITT, including timing of initiation and completion, infant elimination signalling, and associations with bladder and bowel dysfunction.MethodsAn integrative review methodology was employed. Comprehensive searches of Scopus, Medline, CINAHL, Web of Science, PsycINFO, and Google Scholar identified relevant studies. Two reviewers independently screened and appraised studies using GRADE and JBI tools.ResultsOf 2,069 studies identified, 21 met inclusion criteria. Six observational studies reported reduced rates of bladder and bowel dysfunction when AITT was practised.DiscussionAITT is widely practised in low-income, non-English speaking countries. While observational studies suggest a potential protective effect on bladder and bowel health, the evidence is at serious risk of bias. Further prospective research in high-income contexts is warranted.”

5. 5

   Toilet training and bowel habits in children up to 4 years: Insights from a population-based prospective cohort study.

   JPGN reports (Huijgen et al.)Published Mar 6, 2026Checked Oct 11, 2026

   “Sex, maternal education level, and the child's ethnic background were associated with having started toilet training by 24 months (girls: 1.48 [1.31-1.67], high compared to low educational level: 0.65 [0.47-0.91], and Turkish, Surinamese, Antillean, and other (outside Europe), compared to Dutch: 1.71 [1.26-2.32], 1.73 [1.29-2.31], 3.79 [2.04-7.05], and 1.53 [1.23-1.91], respectively). Only sex and ethnic background showed associations with having completed toilet training by 36 months. Reported defecation frequency varied widely in early life but stabilized to 1-2 times daily for 81.3% of children by 24 months. Infrequent bowel movements and predominantly hard feces were present in up to 6.3% and 14.3%, respectively.ConclusionThis study demonstrates that 60% of children are toilet-trained by 36 months. Additionally, it provides insights into healthy children's bowel habits and toilet training milestones, highlighting variations by sex, socioeconomic status, and ethnicity, which can help identify abnormal patterns.”