Why are so many four-year-olds not potty-trained before starting school?
Guidance says training usually starts around 18–24 months and most children finish by four, but many now reach school untrained, and a decision chart was linked to finishing earlier.
Covers: The reported rise in delayed potty training among preschool-aged children, the developmental, behavioural, family and environmental factors linked to it, and what paediatric guidance says about typical timing. It does not give individual medical advice or diagnose continence problems.
Also answers: Why are more four-year-olds starting school in nappies? · Why aren't four-year-olds potty-trained before school? · What causes late potty training in children? · Are children potty-trained later than before?
- One page for this question6 other ways of asking lead here
- 4 independent sourcesEvery claim links to what supports it
- 1 connected pageWhat's learned there shows up here
- Clean discussionScreened before anything appears
The short answer
Evidence-backed AI-prepared starting mapDevelopmental norms place readiness for toilet training between roughly 18 and 24 months, and in much of the developed world training typically begins between 18 months and two years, with most children fully trained by age four. Yet many children now reach school without this self-care skill, and because kindergarten admission generally does not depend on toilet training status, schools are absorbing the task. A 2026 multicentre prospective study of 354 children found that using a toilet-training initiation decision chart was associated with completion at a median age of 37.5 months versus 40.8 months in the control group (P=0.002), with no significant correlation between the age training began and how long it took to complete.123
- Evidence 15
Did this answer your question?
Be the first to voteIn brief
A decision chart for when to start training was linked to completion about three months earlier (median 37.5 vs 40.8 months) in a 354-child study, though only 43 children completed training during it.3
Evidence-backedDelayed training is associated with child readiness, developmental disabilities, poverty, lower parental education, and higher rates of single and teenage parents.1
Evidence-backedKindergarten admission generally does not depend on toilet training, so schools are expected to accommodate untrained children even though education is their main purpose.1
Evidence-backedNo single training approach is universally effective, and comparative research on techniques is lacking.2
Evidence-backed
At a glance
The picture in numbers
Live · updated just now
- Chart-guided37.5 months
- Control group40.8 months
354 children
43 children
21 studies
The evidence behind it
5 sources- Reviews of many studies1
- Other studies and data3
- Background1
When it was published
Newest from 2026
| Source | Kind | Year |
|---|---|---|
| Classroom Toileting: A Collaborative Effort. | Other studies and data | 2024 |
| Assisted Infant Toilet Training and Bladder and Bowel Health: A Global Integrative Review. | Reviews of many studies | 2025 |
| A multicenter prospective evaluation of a decision chart for toilet training initiation. | Other studies and data | 2026 |
| Toilet training (Wikipedia) | Background | Unknown |
| Toilet training and bowel habits in children up to 4 years: Insights from a population-based prospective cohort study. | Other studies and data | 2026 |
The community around it
No one has added to this page yet. Firsthand experience, a newer study or a different reading of the numbers would show up here, credited to you.
What it means for you
Which fits you?
Pick the situation closest to yours. Each answer says what it rests on.
If you want to know when training typically starts and finishes
norms describe readiness from 18–24 months, with most children in the developed world fully trained by age four, though occasional accidents can continue.12
Evidence-backedIf you are deciding when to begin training and want a structured cue
a decision chart keyed to developmental stage was associated with earlier completion (median 37.5 vs 40.8 months) without evidence that it rushed initiation or prolonged training.3
Evidence-backedIf you work in a school receiving untrained children
the school-nursing literature suggests nurses can lead classroom toileting programmes in collaboration with administrators, teachers, staff and parents.1
Evidence-backedIf you are weighing early cue-based training
observational studies in low- and middle-income settings report less bladder and bowel dysfunction with assisted infant toilet training, but the evidence is at serious risk of bias and has not been confirmed prospectively in high-income countries.4
Evidence-backedIf you are choosing a training method
techniques vary and no single approach is universally effective, so trainers may need to adjust to what works for the individual child.2
Evidence-backedThe full story · 2 chapters
01
What paediatric and developmental guidance says about timing
AI summary:Norms put readiness at 18–24 months and most children finish by four, while a decision chart was linked to earlier completion.
Evidence-backed: Standard developmental norms describe readiness for toilet training as emerging between 18 and 24 months. In much of the developed world, training is typically begun between 18 months and two years, and the majority of children are fully trained by age four, though occasional accidents may continue past that point. Attitudes and practices have shifted substantially over recent history and vary by culture and demographics, and recommendations on technique differ considerably, with no single approach considered universally effective.12
Evidence-backed: A 2026 multicentre prospective evaluation tested a toilet-training initiation decision chart against conventional school practices across 354 enrolled children. Median age at completion was significantly younger in the chart-guided group, 37.5 months versus 40.8 months (P=0.002). The study found no significant correlation between the age at which training was initiated and the duration needed to complete it, and its authors conclude the chart may help initiate training at an appropriate developmental stage without either rushing the start or prolonging the process.3
02
Factors linked to delayed training
AI summary:Delayed training is tied to readiness, disabilities, poverty, parental education and family factors, and schools absorb the task.
Evidence-backed: A school-nursing review lists multiple contributors to delayed toilet training: the child's own readiness, developmental disabilities, poverty, lower parental education levels, and higher rates of single and teenage parents who may lack parenting skills that include toilet training. It notes that children are generally accepted into kindergarten regardless of toilet training status, so schools must be prepared for children who lack this self-care skill, and that while school staff are willing to help, the primary purpose of school is education. The review suggests school nurses can support classroom toileting programmes by working with administrators, teachers, staff and parents.1
Evidence-backed: An integrative review of assisted infant toilet training, which is common in low- and middle-income countries, found six observational studies reporting reduced rates of bladder and bowel dysfunction where the practice was used. The authors caution that this evidence carries serious risk of bias and call for prospective research in high-income settings. This points to early, cue-based training as a possible protective factor, but it does not establish that later training causes continence problems.4
Your turn
Have your say
See where others stand. Join free to add your perspective. One answer per account.
How do you feel about this?
No votes yetQuick questions from connected pages
Before you go
What to remember
Try to recall each hidden figure before you reveal it. Remembering, not rereading, is what makes it stick.
Developmental norms put readiness for toilet training at months, and most children in the developed world are fully trained by age four — yet many now reach school without the skill.
A decision chart for when to start training was linked to completion about three months earlier (median 37.5 vs 40.8 months) in a -child study, though only 43 children completed training during it.
Delayed training is associated with child readiness, developmental disabilities, poverty, lower parental education, and higher rates of single and teenage parents.
Your reading
0 of 2 chaptersThis answer keeps changing
When new evidence or a better source comes in, this page is updated (it's on version 2, last changed 1 hour ago). Follow it to be told when that happens.
Up nextIs a four-year college degree still worth the cost?Is a four-year college degree still worth the cost in terms of financial returns, career outcomes, and personal development?Ask this Sylo
Still wondering about something?
Answers come only from this page's reviewed material, with citations, and say plainly when the page doesn't cover it yet.
Behind this page
Who's adding to it, where it comes from, how it changed and what would make it better. Always open to everyone.
Discussion
Sources
Numbers match the citations in the article. A working link isn't proof that a page supports a claim; check the quoted passage and date.
- 1Classroom 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.”
- 2Toilet 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.”
- 3A 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.”
- 4Assisted 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.”
- 5Toilet 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.”
How it changed
Published 1 time since Oct 11, 2026.
- Version 2Oct 11, 2026Live now
AI-prepared Starting Map from live research.
- First published version.
Help improve it
The brief is open about what's uncertain. These are the specific gaps that new material would fill.
Open questions
What share of four-year-olds actually start school without being toilet-trained, and how has that share changed over time? No source here gives prevalence or trend figures.
No answers yet
Which of the listed factors — readiness, developmental disability, poverty, parental education, family structure, or changing cultural norms — accounts for most of any increase, and how do they interact?
No answers yet
Would the apparent protective effect of assisted infant toilet training on bladder and bowel health hold up in prospective studies in high-income countries?
No answers yet
What is the appropriate division of responsibility between families and schools when a child arrives untrained, and what support do school staff need?
No answers yet
Around this topic
Sylos connect: narrower topics report up to broader ones, so what's learned in one place shows up where it matters.