The timing of toilet training: What's the best potty training age?

© 2006-2020 Gwen Dewar, all rights reserved

What is the right potty training age? The answer depends on you, your goals, and the characteristics of your child. In this article I cover:

  • the "normal" age to train, and how this age varies across cultures and historical time periods;
  • the developmental effects of toilet training, and why when you train matters less than how you train;
  • the pros and cons of toilet training during early infancy;
  • the potential difficulties of training children between 12-18 months;
  • guidelines for training children between 18-24 months; and
  • the pros and cons of waiting until children are older than 24 months.

Getting started: What's the normal age to begin toilet training a child?

"Normal" is a slippery concept. It varies from one culture to the next, and it changes over time.

For instance, in much of the non-Western world, toilet training begins very early -- sometimes within weeks of birth. Without being punished or abused, babies learn basic toilet training skills before they can walk. And they never wear diapers.

The situation is very different in places like the United States, where children may wear diapers for two to three years, or even longer.

In a recent American study, most parents said they didn't even begin toilet training until their children were between 24 and 36 months old (Sejkora et al 2020). 

And a study in Belgium found that approximately 90% of children weren't toilet trained until they were at least 24 months old, and 40% weren't trained until they were at least 30 months old (van Nunen et al 2013).

Has it always been this way? Have Americans and other Westerners always been inclined to delay potty training until at least 24 months?

No. Back in the 1940s, most American children were out of diapers by 18 months (Martin et al 1984). The shift to delayed toilet training happened later, during the latter half of the twentieth century (Largo et al 1996; Bakker and Wyndaele 2000; Horstmanshoff et al 2003). 

So what should a contemporary, 21st century parent do? Train early, or late?

There isn't any single, correct answer. It depends on your goals and lifestyle, and on the characteristics of your child.

But the first step in making a decision is to clear up any questions or concerns you might have about your child's long-term psychological well-being and physical health.

Does the timing of training have any lasting developmental impact on children? Let's dig into it.

Taming your worries: What research tells us about the developmental consequences of training

1. Infant training -- as practiced in traditional cultures -- isn't linked with any long-term problems.

In more than a decade of following the research on toilet training, I haven't found any scientific evidence that infant training is harmful. On the contrary, studies suggest that it's beneficial. 

The immediate advantages are pretty obvious. Babies never wear diapers, so they avoid the rashes and infections associated with diapers. Their parents save time and money on diapering. And going diaper-free is good for the environment.

But there are other, less obvious advantages too.

Research hints that children are less likely to experience recurring urinary tract infections if they were toilet trained during infancy. Why?

It's probably because toilet-trained infants learn to empty their bladders completely -- eliminating any residual urine that can harbor bacteria. Children who don't begin training until after the age of 24 months may not learn this habit until their third birthdays (Duong et al 2013).  

And there's evidence that infant trainees are at lower risk for developing problems with incontinence later in life (Wang et al 2020).

2. Training during a child's second year -- between 12 and 24 months --  can be trickier. But as long as the training methods are developmentally appropriate, kids don't seem to be at any higher risk for problems.

When you train children this age, the training includes asking them to sit on a potty chair. And some kids aren't ready or motivated to cooperate. But if your child is ready (see below), this can be a perfectly good potty training age. 

3. When parents begin toilet training later -- during a child's third year, or even later -- kids might be at higher risk for incontinence problems as they get older. But there's no evidence that starting late causes any emotional or psychological problems.

Studies in multiple countries have reported links between late training and a higher probability of experiencing daytime incontinence after the age of 5 years (e.g., Li et al 2020; Joinson et al 2009). But researchers haven't found any evidence that late training is linked with emotional problems or psychopathology (Axelrod et al 2020).

So that's the good news. Regardless of the potty training age you choose, you don't need to worry about warping your child's psychological development.

From the standpoint of protecting your child's health and well-being, the most important factor isn't your child's chronological age.

What really matters is choosing method(s) that are appropriate to your child's developmental level, and adjusting your approach if your child shows resistance, or encounters difficulties.

[For help with these things, see my article about potty training methods, and this Parenting Science guide to coping with common toilet training problems]. 

So you won't make your kid neurotic by choosing the "wrong" potty training age. That's reassuring, right? But there are other factors to weigh. What's best for your family?

In the rest of this article, I will compare the advantages and disadvantages associated with training four different potty training age groups:

  • Infants (0-12 months)
  • Young toddlers (12-18 months)
  • Older toddlers (18-24 months)
  • Children over 24 months

Choosing the right potty training age: What you need to know about your options

Infant potty training: 0-12 months

It sounds bizarre to many Westerners. But for parents in places like India, China, and East Africa (deVries and deVries 1977; Boucke 2002), the traditional potty training age is early infancy.

In these societies, parents learn to recognize their babies' body signals and to use these signals to anticipate when their babies eliminate.

When the infant is ready to go, the parent holds him over a sink, bowl, toilet, or the open ground. As the infant voids, the parent makes a characteristic sound or gesture. The baby learns to associate this parental sign with voiding, and, eventually, the parental sign becomes an invitation to void. When the baby feels the urge to go, he learns to hold back for a brief time until his parent gives him the "all clear."

[Read more about the traditional method of infant training -- often called "elimination communication" -- this Parenting Science article.]

Of course, this isn't what many people mean by "toilet training." Babies can't walk or flush or wipe themselves, so infant toilet training is necessarily a more modest affair: staying dry with lots of parental supervision.

Is it worth it -- all that parental supervision and vigilance?

That's something that parents will have to decide for themselves. But there are definitely some advantages to consider.

To the degree that babies avoid diapers, they also avoid diaper rash and diaper-associated infections.

In addition, as mentioned above, there's reason to think that infant toilet training may help lower a child's risk of recurring urinary tract infections and daytime incontinence.

And some parents may see infant training as a worthy trade-off. Yes, you have to be very vigilant now. But by training your child early, you save yourself a lot trouble later.

When kids grow up wearing diapers, they don't learn to pay special attention to their body signals, like the sensation of a full bladder. In fact, they may learn the opposite -- to actively ignore those feelings. 

Kids may also develop a sense of familiarity and comfort in wearing diapers -- making them more reluctant to wear underpants.

These factors can make it harder for older children to learn toileting skills. They have old habits to break. By contrast, if you start very early, your baby won't have any bad habits to overcome. 

When exactly does infant training begin?

Traditionally, infant potty training starts during the first six months after birth (Boucke 2003; Duong et al 2013).  

Can you start infant training after 6 months?

Yes. But it might be more difficult, especially if your baby has learned to crawl or walk.

Once babies discover mobility, they are less patient about sitting still on a potty chair. And there's the additional problem of breaking old habits. An older infant may have already become accustomed to diapers, making the transition harder (Boucke 2003).

Is this "traditional" method the only way to approach infant toilet training? What if you want to sit your child on a potty chair?

There's another method that is appropriate for babies who have learned to sit up -- straight and steady -- without support. If you're interested in this chair-based training method, check out this Parenting Science article, where I explain the procedure in detail.

Older infants and young toddlers (12-18 months)

Back in the 1920s and 1930s, European and American parents often began toilet training between 12-18 months (Bakker and Wyndaele 2000). 

Nowadays, European and American parents tend to wait longer. Why?

It might reflect a desire to wait until children become a little less restless.

Between 12 and 18 months, most children are learning to walk. And kids who are learning to walk may feel too excited to sit still on a potty chair (Brazelton and Sparrow 2004).

In support of this idea, one study found that kids between the ages of 15 and 19 months were more resistant to sitting on potty chairs than were older children (Sears et al 1957).

Parents might also find it more difficult to communicate.

Children this age have very limited language abilities. This can make it harder for parents and children to communicate about body functions. Does your child need to use the potty? It might be hard to tell. And if your child resists using the potty -- if your child tries to "hold it in" -- he or she could end up with constipation, urinary tract infections, or other problems.

But if you are motivated to try toilet training during these months, don't let these considerations put you off. Just pay attention to your child's behavior, and be prepared to make adjustments. 

Avoid toileting training if your child is experiencing constipation, urinary difficulties, or any other problems with elimination. Get that sorted out first.

Then -- when your child is healthy and ready to begin -- you can try this infant potty-chair method. If your child resists, or becomes upset, back off and wait. 

And keep realistic goals. Children under the age of 18 months are not going to achieve true toileting independence. This potty training age is about staying dry with careful parental supervision and assistance. 

If you decide to skip these months -- delay training for a later date? You can still put the time to good use.

The interval between 12-18 months is the perfect time to start thinking about toilet readiness -- a set of skills and interests that will help your child master advanced toilet skills later on. You can make potty training easier if you actively prepare your child months in advance. Find tips on potty training preparation here.

Potty training between 18-24 months: Should you wait for signs of "toilet readiness"?

Suppose your child is between 18 and 24 months old. Is this a good potty training age?

The conventional answer from Western pediatricians is, "yes -- as long as your child is showing signs of toilet training readiness."

So what are these signs?

I've compiled a checklist, based on the recommendations of several sources, including the American Academy of Pediatrics. You can see the full checklist here.

But the quick answer is that the signs include major developmental milestones (like the ability to walk), as well as evidence that your child is motivated: Your child asks to use a potty chair, or tells you that he or she wants to wear "big kid" underpants.

How important are these signs? Should you really wait for them?  

The answer depends on what your goals are.

If your goal is for your child to walk into the bathroom and sit on the potty independently, then you obviously should wait until he or she can walk.

If you're interested in a more modest goal -- something closer to the parent-assisted dryness we've discussed so far -- then you don't need to wait for all of these advanced signs of "readiness."

But keep in mind. There's one sign of readiness that seems especially predictive of long-term success: A child's awareness, and ability to communicate about, body signals.

In a study tracking the progress of 270 toddlers, researchers found that only three signs of readiness predicted toilet training success. One promising sign was if a child could pull his or her pants on and off. Another was if a child showed pride in doing things independently.

But the most predictive sign of them all was if a child "expresses a need to evacuate and shows awareness of the need to void or have a bowel movement" (Wyndaele et al 2020). 

So if your child isn't yet showing these abilities, it makes sense to foster them. Talk with your child about the sensations that accompany elimination, and teach your child the vocabulary needed to express these feelings.

For tips about this -- and about other aspects of toilet training readiness -- see my article, "Toddler potty training: How to get your child ready."

And whenever your child finally begins, remember that it will take a long time before your child has the skills and maturity to go "solo."

Even after they complete training, most children aren't ready to go to the bathroom unattended until they are at least 36 months old (Gesell and Ilg 1943; McKeith 1973; Bakker 2002).

Potty training after 24 months: Is it better to wait?

As I noted at the beginning of this article, kids in the United States and other Western countries are being trained later. The normal potty training age is 24 to 36 months. Is this a good thing?

There's at least one, potential advantage to waiting this long. It might result in a faster training time. When researchers tracked the development of more than 250 American children, they found kids tended to complete training faster if they started after the age of 24 months (Schum et al 2002). 

But it might not work out that way for everyone. When kids wear diapers for years, they can become accustomed to ignoring their body signals. They learn to feel comfortable wearing diapers. These are habits, and habits can be hard to break. 

And as I've noted above, delayed training is linked with an increased risk of bladder problems, including incontinence, later in life (Barone et al 2009; Bakker 2002, Bakker et al 2002; Joinson et al 2009; Li et al 2020; Wang et al 2020).

So these are considerations to weigh and balance. The most important things to remember?

Experts agree that you should choose a time when your child is 

  • healthy (no diarrhea or constipation, for example);
  • relaxed (not stressed by new changes, like a move or new baby); and
  • cooperative (not going through a rebellious phase).

And it's a good idea to actively prepare your child for toileting training. 

Beyond this, your choice of timing is unlikely to cause any long-lasting behavior problems. What matters most is the way you train your child, and how you handle setbacks.

For more information, check out these Parenting Science articles:

Copyright © 2006-2020 by Gwen Dewar, Ph.D.; all rights reserved.
For educational purposes only. If you suspect you have a medical problem, please see a physician.

References: Choosing the right potty training age

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Content of "The timing of toilet training: What's the best potty training age?" last modified 12/2020