Potty Training Before 24 Months May Backfire, According to Research on What Actually Works

A friend of mine started potty training her 18 month old because her mother-in-law said "in my day we had all of you out of nappies by your second birthday." Three weeks in, the toddler was having eight accidents a day, had become terrified of the toilet, and had developed constipation from withholding. My friend was in tears. The toddler was in tears. No one was winning.

They stopped. Waited six months. Tried again at 26 months. Fully trained in a week. No tears. No accidents. No constipation.

This is exactly what the paediatric literature predicts. And yet every generation of parents gets told by the previous one that potty training used to happen earlier, faster, and without drama. Let me walk you through what the research actually says, and what "readiness" looks like when you know what you are watching for.

What the research actually shows

Paediatrician T. Berry Brazelton's foundational research established that starting potty training before a child is physiologically and emotionally ready extends the process, not shortens it. Studies from the American Academy of Pediatrics have since consistently shown that children who start earlier take longer to fully train. Children who start between 27 and 32 months often train within days to weeks. Children who start before 24 months often take months.

There are three separate readinesses that need to align before potty training can work, and they develop at different rates:

Physiological readiness. The bladder and bowel sphincter muscles have to be mature enough for the child to physically hold and release on cue. This typically happens between 22 and 30 months. You cannot train what the body cannot yet do.

Cognitive readiness. The child needs to understand cause and effect, be able to follow simple instructions, and recognise the sensation of needing to go before it happens. Most toddlers develop this between 24 and 36 months.

Emotional readiness. The child has to be willing. Forcing a toddler who is not emotionally ready creates exactly the dynamic my friend experienced. Fear, withholding, accidents, and regression.

The most important factor in successful toilet training is not the age at which you begin, but the child's readiness. Beginning before all three readinesses are present prolongs the process and increases the likelihood of setbacks.Adapted from AAP and Brazelton-based paediatric guidance, widely replicated in current literature

There is no prize for starting early. There is no developmental benefit. Children who start at 30 months and fully train in a week have exactly the same long-term outcomes as children who start at 22 months and train over six agonising months. The only difference is how hard it was for everyone.

The 6 readiness signs

These are the signs paediatricians actually tell you to look for. Your child does not need all six, but they should be showing most of them.

The one that matters most: If your child hides to poo, or goes off to a quiet corner and then announces they have done one, they are showing strong readiness. They understand the sensation and are responding to it. That is the golden sign.

The 4-step approach that works

When things go wrong (and what to do)

Withholding. The most common complication of too-early training. Child refuses to poo on the toilet, holds for days, then becomes constipated, which makes pooing painful, which reinforces the holding. If this happens, go back to nappies for bowel movements only. Let them feel safe.

Regression after starting. A child who was doing well suddenly has multiple accidents a day. This is usually a sign of stress (new sibling, moving house, starting nursery) or illness. Back off the pressure, stay warm, wait it out. It almost always passes.

Night training not happening. Night dryness is physiologically different from day dryness. It depends on the body producing enough antidiuretic hormone at night, which many children do not develop until 4 to 6 years old. Bedwetting up to age 5 or 6 is within normal range and is not a training failure.

Frequently asked questions

The permission to wait

I want to give you permission to ignore everyone who asks you when you are going to start potty training. Your mother. Your mother-in-law. The other mums at the playground. The woman at the nursery. All of them. The only question that matters is whether your child is ready. If the answer is no, the answer is wait.

You are not behind. There is no race. The children who start at 30 months and train in a week are indistinguishable, five years later, from the children whose parents suffered through six months of training at 18 months. The only difference is how much the whole family had to suffer to get there.

Wait. It is the most powerful tool you have.

What age did your child show readiness? Share in the comments. It helps other parents calibrate.