The Science Behind Potty Training

At a Glance: Research-Backed Potty Training Trips

• The best age to start toilet training for most children is between 27 and 32 months.
• Research shows that both the Child-Oriented method and Azrin & Foxx’s method are effective ways to potty train.
• Distractions, inconsistent limits from parents, health problems, and age can all cause difficulty with potty training.
• Many children can’t stay dry all night long until age 8 or 9, and they will need to get up to potty at night.
• Limit fluids in the evening and wake your child to potty before you go to bed to help avoid nighttime accidents.

Potty training is a hot topic for every parent, so we reached out to a Charlottesville expert. Not only does Dr. Cara Goodwin have the academic training with a PhD in Child Psychology, but she is also a mother of 4. Below, she shares what parents need to know about toilet training.

When Is the Best Time to Start Potty Training?

According to the research, the sweet spot for toilet training seems to be between 27 to 32 months for most children. However, every child is different.

You should base your timeline on your child’s individual signs of readiness. These signs include:

• Staying dry for longer periods of time
• Seeming uncomfortable with soiled diapers
• Interest in the toilet or wearing underwear
• Ability to follow simple instructions

Is It Better to Start Potty Training Younger?

Starting younger isn’t necessarily better when it comes to potty training.

Research has found that children who are trained at younger ages (in this case, before 27 months) are no less likely to experience accidents or to refuse to poop than children trained after 27 months. However, this study also found that the younger a child is when beginning the process of toilet training, the longer the process will take to complete.

Children who started potty training between 18 to 24 months took 13 to 14 months on average to complete training. Children who started toilet training after 27 months took 10 months or less on average to complete training.

A Swedish study also found that only 31% of 2-year-olds have sufficient bladder sensation to successfully toilet train. On the other hand, 79% of 3-year-olds do.

However, another line of research has found that children trained at older ages may have difficulty with potty training. In particular, children who are trained after 32 months may be more likely to have accidents and difficulty with toilet training. So timing does matter, but that 27 to 32 month window (between ages 2 and 3) seems to be ideal.

What Is the Best Way to Potty Train?

Any parent who has googled “potty training” will find books and websites that claim to know the ONLY effective method for toilet training your child. But is there any research that actually supports these claims?

Surprisingly, a systematic review of toilet training conducted by the Agency for Healthcare Research and Quality (AHRQ) found that research on this topic is extremely limited. The big take-away message is that there is no strong research evidence for a “right” way to toilet train.

However, the authors did find evidence that the Child-Oriented method and Azrin & Foxx’s method of toilet training resulted in effective toilet training for most typically developing children.

Both methods suggest that parents toilet train between 2 and 3 years of age. Otherwise, the methods are very different. The Child-Oriented approach is designed to be gradual and led by the child. Azrin & Foxx’s method is intensive and led by the parents.

Let’s take a look at both.

The Child-Oriented Potty Training Method by Dr. Brazelton

The Child-Oriented approach (developed by Dr. Berry Brazelton in 1962) is a gradual approach. The idea is tolet the child decide when they are ready to use the toilet. This method involves showing your child the toilet and modeling toileting for them. The parent allows the child to sit on the toilet with no pressure.

After a few weeks of this, the parent then empties a diaper into the toilet. The parent then removes the child’s diaper and pants for short time intervals and the child is encouraged to use the toilet whenever they need to. If the child successfully uses the toilet, the parent would then put the child in training pants.

Throughout this process, the parent praises any success and avoids criticism. Want to learn more about this method? You can find the book Toilet Training-The Brazelton Way at local book retailers or at the library.

The Azrin & Foxx Potty Training Method

The Azrin & Foxx method (developed in 1973) is a parent-led approach. It’s designed to be more intensive and quicker than the Child-Oriented approach.

This approach involves putting the child immediately in underwear and encouraging the child to drink lots of liquid. Then, show the child the expected toileting behavior by:

• Using a doll
• Providing consistent rewards for successful toileting
• Prompting the child to regularly try to use the toilet
• Guiding the child to the bathroom after an accident

For more information, you can find their book, Toilet Training in Less Than a Day, at local book retailers or your local library.

Which Potty Training Method Is Better?

Only one study directly compared the Azrin & Foxx method to the Child-Oriented method. It found that the Azrin & Foxx method was associated with reduced accidents and increased rates of successful toileting. However, another study found that children demonstrated more temper tantrums in response to the Azrin & Foxx method, suggesting it may be too intensive for some children.

What’s the big take-away? There is no single “right” method to toilet train according to the research.

Choose whatever method seems best for your child and your household, or mix the two together. And don’t let anyone tell you that you are doing it wrong!

Why Do Some Children Struggle with Potty Training?

What might predict whether your child will have difficulty with toilet training?

Most children typically begin toilet training sometime between 21 to 36 months. Only 40 to 60 percent of children are fully toilet trained by 36 months. So, if your child is struggling with toilet training, know that you are not alone!

Research has found that difficulty with toilet training has been associated with a few different things:

• Distractions: The presence of younger siblings during toilet training
• Consistency: Parents with difficulty setting limits
• Age: Training at older than 42 months of age

Also, a very interesting study found that reducing shame around bowel movements may reduce the time to toilet train. In this study, parents were encouraged to praise the child for having a bowel movement before toilet training. They were also encouraged to avoid using words to negatively refer to defecating, such as “stinky” or “gross.”

The parents who used this more positive approach had children who were successfully toilet trained more quickly.

Finally, if your child continues to struggle with potty training, check with your pediatrician. You might need to rule out underlying medical issues. Research shows that children with lower urinary tract symptoms were more likely to be toilet trained at a later age.

In addition, hard and painful bowel movements have been found to be associated with “stool toileting refusal,” also known as not wanting to poop on the toilet. This is a condition that impacts up to 1 in 4 children. Improving your child’s diet and fluid intake, which means making sure they have plenty of fiber and water, may also help them use the toilet more easily.

Do Boys Have More Trouble with Potty Training?

You may have heard the claim that boys have more difficulty with potty training than girls. But is there any truth to it?

There is some science to back up this parenting myth. Research finds that girls are typically toilet trained 2 to 3 months before boys (32.5 months vs. 35 months). They also begin showing readiness signs 2 months before boys (24 months vs. 26 months). However, the research didn’t identify causes for this, so we don’t know whether the difference is biological, developmental, or social.

What About Nighttime Potty Training?

Most children are not developmentally capable of remaining dry at night until 4 or 5 years old. A large study found that about 30% of children experience bedwetting at 4.5 years and about 9.5% still experience it at 9.5 years. Research has also found that children attain nighttime dryness an average of 10 months after achieving daytime dryness.

This means that some kids eventually start staying dry at night on their own, without specific nighttime training. Others will start feeling the same physical signals in their body that they feel during the daytime and wake up to potty during the night. (Younger kids may need to come get a parent to help with this.)

If your kid needs a little more help with nighttime potty training, however, there are steps you can take.

Strategies for Potty Training at Night

If your child struggles with nighttime accidents after the age of 5 years, there are things you can do to help them stay dry at night. The easiest strategies to try are:

• Wake up your child to use the bathroom before you go to bed yourself.
• Limit fluid intake before bedtime.

Potty Training Alarms

If those strategies do not work, a great evidence-based strategy is an alarm that wakes your child up when they start urinating. One of the most common of these alarms is called TheraPee. Six randomized controlled trials (considered the “gold standard” of study designs) have found that bedwetting alarms are very effective in helping children to stay dry at night.

Specifically, these studies have found that 77% of children using these alarms are able to stay dry for 14 nights in a row. Only 2% of children in the study without these alarms had 14 dry nights in a row. Children in these studies ranged in age from 8 to 10 years and the treatment lasted between 10 to 20 weeks.

How to Get Through Potty Training

Nearly all parents face the challenge of potty training at some point. And depending on your child’s age and health, as well as your own personality, it can be a daunting one! But there are resources out there to help. Before you dive in, take a look at some research-backed approaches to find that one that resonates with you the most.

Talk to your pediatrician if you need a little extra help. They can suggest strategies that are best suited to your child’s needs. And don’t forget to talk to the other parents in your life! Whether you need a tool, a tip, or just a sympathetic ear, there’s a good chance your parenting village can provide.

Looking for support in the toddler years? Read on for more great resources from CharlottesvilleFamily including mini day camps for little ones, Mommy & Me Classes, early learning tips, local health professionals, helping young children to understand the word “No,” and more!

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DR. CARA DAMIANO GOODWIN, PhD, is a licensed clinical psychologist and a Charlottesville mother to four children. She received a PhD in child clinical psychology from the University of North Carolina at Chapel Hill, a Master’s in Developmental Psychiatry from Cambridge University, and a Master’s in Child Psychology from Vanderbilt University. She specializes in child development and has spent years researching child psychology and neuroscience and providing therapy and clinical services for children of all ages. Dr. Goodwin translates recent scientific research into information parents can access and implement in their everyday lives through her Instagram account and her website.

References on Potty Training

Azrin, N., & Foxx, R. M. (2019). Toilet training in less than a day. Gallery Books.

Bakker, E., Van Gool, J. D., Van Sprundel, M., Van Der Auwera, C., & Wyndaele, J. J. (2002). Results of a questionnaire evaluating the effects of different methods of toilet training on achieving bladder control. BJU international, 90(4), 456-461.

Barone, J. G., Jasutkar, N., & Schneider, D. (2009). Later toilet training is associated with urge incontinence in children. Journal of Pediatric Urology, 5(6), 458-461.

Blum, N. J., Taubman, B., & Nemeth, N. (2003). Relationship between age at initiation of toilet training and duration of training: a prospective study. Pediatrics, 111(4), 810-814.

Blum, N. J., Taubman, B., & Nemeth, N. (2004). Why is toilet training occurring at older ages? A study of factors associated with later training. The Journal of Pediatrics, 145(1), 107-111.

Brazelton, T. B. (1962). A child-oriented approach to toilet training. Pediatrics, 29(1), 121-128.

Brazelton, T. B., & Sparrow, J. (2004). Toilet Training-The Brazelton Way. Da Capo Press.

Butler, R. J., & Heron, J. (2008). The prevalence of infrequent bedwetting and nocturnal enuresis in childhood: a large British cohort. Scandinavian Journal of Urology and Nephrology, 42(3), 257-264.

Glazener, C. M., & Evans, J. H. (2002). Desmopressin for nocturnal enuresis in children. Cochrane Database of Systematic Reviews, (3).

Foxx, R. M., & Azrin, N. H. (1973). Dry pants: A rapid method of toilet training children. Behaviour Research and Therapy, 11(4), 435-442.

Jansson, U. B., Hanson, M., Sillén, U., & Hellström, A. L. (2005). Voiding pattern and acquisition of bladder control from birth to age 6 years—a longitudinal study. The Journal of Urology, 174(1), 289-293.

Klassen, T. P., Kiddoo, D., Lang, M. E., Friesen, C., Russell, K., Spooner, C., & Vandermeer, B. (2006). The effectiveness of different methods of toilet training for bowel and bladder control. Evid Rep Technol Assess (Full Rep), 147, 1-57.

N.C.G.C. (2010). Nocturnal enuresis: the management of bedwetting in children and young people.

Stadtler, A. C., Gorski, P. A., & Brazelton, T. B. (1999). Toilet training methods, clinical interventions, and recommendations. Pediatrics, 103(Supplement 3), 1359-1361.

Taubman, B. (1997). Toilet training and toileting refusal for stool only: a prospective study. Pediatrics, 99(1), 54-58.

Taubman, B., Blum, N. J., & Nemeth, N. (2003). Stool toileting refusal: a prospective intervention targeting parental behavior. Archives of Pediatrics & Adolescent Medicine, 157(12), 1193-1196.